This, of course, is the formula that Romney relied on to undermine Newt Gingrich when the former House speaker emerged as his chief rival in the run-up to last month’s Florida primary. In a way, Santorum is in basically the same position Gingrich was then, frantically playing financial and organizational catch-up after a breakthrough victory. So Gingrich’s Florida futility seems telling: Even with a major boost in fund-raising and a $5 million check from Sheldon Adelson, he was still outspent by Romney by an estimated $12 million on ads in Florida.

Now it’s Santorum’s turn to face this kind of disparity. Money has been flowing into his campaign like never before this past week and he’s found his own super PAC benefactor, but there’s just no way he and his allies will even come close to matching what the Romney forces will be able to spend in Michigan, Ohio and any other state they deem crucial to their strategy. What’s worse, the Wall Street Journal reported today that Adelson, who’s been sending signals behind the scenes that he wants to stay loyal to Gingrich but also wants to help Romney, may have found a way to reconcile his inner-conflict — funding ads that are ostensibly aimed at helping Gingrich but that actually do Romney a big favor by bashing Santorum.

If there’s a ray of hope for Santorum, it can be found in the content of Restore Our Future’s new attack ad, which blasts Santorum for votes as a senator to raise the debt ceiling and allow convicted felons to vote and for earmark requests. What’s striking is how little the Romney forces have to work with; after all, you can always find something to put in a 30-second attack ad, but the material being used here has an obscure/random feel to it. Santorum, with his generally consistent conservatism and lack of serious personal baggage, just doesn’t isn’t the same ripe target as Gingrich. When the Romney campaign needed to attack him, the ads literally wrote themselves:

So it’s fair to wonder how much punch the anti-Santorum ads will pack. Plus, Santorum — again, unlike Gingrich — is actually a generally competent candidate running a generally competent campaign. Which means his side wasted no time mounting a response to the Romney blitz:

Santorum doesn’t have the money to saturate the airwaves with ads like this. But his real aim may be to them to generate viral and free media attention and to convince influential conservatives around the country to rally to his defense and push the Mitt-as-bully narrative.

On the one hand, support for gay marriage among New Jersey voters is solid — 52 percent favored it and 42 percent opposed it in one recent poll, while another pegged the margin at 48-37. Among independents, support is even higher. And the trajectory seems clear: Just five years ago, those overall numbers were reversed when the topic was polled. Given how rare Republican victories in New Jersey are (Christie’s 2009 win marked just the fifth statewide triumph for the GOP in 37 years, and only the second that was won by more than a point), Christie has to be very careful as he approaches his reelection race. He doesn’t have much margin for error when it comes to alienating swing voters — one of the reasons he was so colorful and adamant in denying interest in the presidential race last year — and swing voters in New Jersey are generally fine with gay marriage.

But Republican voters nationally are not, and it will be a long time before they are (if they ever are). So if he wants to preserve his viability for ’16, Christie cannot be known as the New Jersey governor who enacted same-sex marriage. But he also can’t position himself as a hard-line, stop-at-nothing-to-derail-it opponent of it; to do so would reek of the cultural conservatism that has made most national Republicans unmarketable in New Jersey and endanger Christie’s reelection prospects. And if he gets the boot in ’13, it could sink whatever ’16 ambitions he has.

Christie’s workaround has been to oppose gay marriage while calling for a public referendum. This has elicited howls from gay marriage supporters, who argue that minority group rights should never be put to a vote, but it has aligned him with a clear majority of voters, who say they like the referendum idea. Of course, a referendum campaign would be long, messy and divisive. And anyway, Democrats in the Legislature have the votes to make sure one never takes place.

But yesterday’s state Senate vote offered another potential way out for Christie: a legislative override. Twenty-four of the chamber’s 40 members — including two Republicans — voted for gay marriage, a surprise result and a significant increase from the last such vote in 2010. It would only take three more votes to reach the number needed to override Christie’s veto. In the Assembly, where the bill will now head, Democrats enjoy a 47-33 majority, with 54 votes needed to override a veto.

The Republican Party in New Jersey has its very conservative pockets, but the cultural moderation of Clifford Case, Tom Kean and Christie Whitman is still prevalent too. There probably are a handful of GOP senators and a scattering of Assembly members who are personally OK with gay marriage and who could survive politically if they voted for it. This presents a Machiavellian possibility for Christie: Wink at them, continue voicing his opposition, then throw up his hands as the Legislature overrides him and takes the issue off the table. As Josh Benson of Capital New York theorizes:

That would be a slap in Christie’s face, for sure. But it’s not clear that it would hurt. After all, if Christie vetoes same-sex-marriage legislation and gets overridden, he’ll be able to tell conservatives one day, when he’s asking for their support, that at least he tried to keep the liberals in check.

The Legislature has until the end of its current term to override Christie — meaning nearly two years. So don’t expect an override any time soon. But if popular support keeps growing and Christie finds himself staring at a difficult reelection race in ’13, it might start to make sense.

But the political world seems to be taking this all in stride. Sure, the newest poll numbers are dominating headlines, but the tone of the coverage suggests that Romney is still seen as the most likely nominee — by far. For all of his woes, Romney is still given a 75 percent chance of winning the nomination by Intrade, with Santorum at just 16 percent. Four factors seem to be driving this conventional wisdom:

1. We’ve been here before: This is the most obvious reason, and it’s been the defining story of the GOP race. One after another, we’ve seen Romney opponents suddenly rise from the back of the pack, vie with him for the lead, promise to unite the Mitt-phobic right, and then … flame out. Significantly, Romney has never experienced the kind of crash that any of these challengers have; he’s had trouble opening up a wide lead in national surveys, but he also seems incapable of falling much below 25 percent. So far, whenever they’ve been forced to focus, Republican voters have ultimately judged Romney’s opponents more unacceptable than him. And when he has scored primary victories, he’s seen his national numbers climb near 40 percent. He’s almost broken away from the pack, in other words. So if past is prologue, Santorum’s surge will prove fleeting, Romney will steady his ship, and we’ll soon be back to talking about Romney’s inevitability. And even if we then go through this cycle again, there’ll still be reason it will end the way it always does, with Romney on top.

2. Money: Romney’s campaign has more of it, and so does the super PAC that’s aligned with him. A lot more of it. Restore our Future, the pro-Romney group, has now committed about $700,000 for television ads in Michigan through early next week, according to the New York Times. A lot more will undoubtedly come after that, since Michigan doesn’t vote until February 28. Restore our Future is also investing in several southern states and in Ohio, where primaries will be held on March 6. Santorum just can’t compete with this. Sure, he’s been on a fund-raising tear since his three-state sweep last week and he has a super-wealthy ally bankrolling a friendly super PAC. But this is similar to what happened to Newt Gingrich a few weeks ago, when a South Carolina victory flooded his campaign with money and prompted Sheldon Adleson to write another $5 million check — and it still wasn’t nearly enough to compete with Romney in Florida.

3. Vicious attacks: They’ve become Romney’s trademark and they go hand-in-hand with his massive bankroll, which can be spent on devastating negative ads as needed. Twice now, Romney and his super PAC have used this technique to combat Gingrich, once in Iowa back in December and again in Florida. And they’re still not letting up on the former House speaker; many of the ads now airing in Michigan are aimed at him. It may be that the Romney forces simply haven’t had time to create anti-Santorum spots yet; or maybe they just want to make sure Gingrich really is marginalized once and for all. Either way, it’s hard to believe that similar attacks against Santorum — who amassed ridiculous popularity in Colorado, Minnesota and Missouri by staying out of the Newt/Mitt sniping — aren’t coming. Romney has already begun trashing the former Pennsylvania senator in speeches and public events. And he’s generally been effective at dismantling his opponents in debates, something he’ll have an opportunity to do with Santorum next week.

4. Endorsements: As Jonathan Bernstein has been pointing out, Santorum’s breakthrough last week — like his breakthrough in Iowa back on January 3 — has not resulted in a flood of endorsements from prominent conservatives, or even a trickle. Especially given the financial disparities at work, it’s critical for Santorum to have loud, influential Republican opinion-shapers making his case and defending him against Romney’s attacks. One of the reasons Gingrich was hurt so badly by Romney’s Florida assault was that GOP elites mostly sat on their hands; they were secretly (or not so secretly) happy to see a candidate they saw as unelectable and unreliable cut down to size. The lack of support for Santorum now suggests that may hold similar reservations about him.

Of course, as I wrote last week, there’s one key difference between Santorum and the others who’ve vied with Romney for the lead this year: He’s a genuinely competent candidate. Not dazzling, but competent. He’s in line with the party base on just about every key issue, doesn’t have much personal baggage, can think on his feet in debates, and deliver a solid stump speech. This is more than can be said for Gingrich, Rick Perry and Herman Cain. This may be Santorum’s best hope: that the desire of the party base to nominate someone other than Romney is so strong that this basic competency is enough to overcome all of the advantages that Romney still enjoys.

Of course, Santorum is hardly the only Republican candidate who’s earned an audition for the role of chief Romney rival, and each one before him has proven spectacularly incapable of capitalizing on the opportunity.

Rick Perry surged to gigantic polling leads when he jumped into the race late last summer, then made a fool of himself in debate after debate and became an afterthought. Herman Cain supplanted Perry sometime during the fall, but fizzled when he couldn’t provide a simple, coherent defense of his signature 9-9-9 plan and after a bizarre sexual harassment saga. Then there was Newt Gingrich, whose erratic style and political past gave his (many) intraparty enemies an endless supply of ammunition — enough to destroy him once in December and then again when he somehow rose from the dead in January.

During all of this, Santorum did have one brief moment of glory, when he gained some last-second traction and won the Jan. 3 Iowa caucuses. But his victory wasn’t announced until weeks later, after he’d fared poorly in New Hampshire and while Gingrich was in the middle of his second surge. Only now is he enjoying the sort of attention and momentum that his Iowa showing should have produced.

Against this backdrop, Santorum’s performance at CPAC this morning was very effective in a very odd way. His speech was hardly great, but it wasn’t bad either. It was a generic, competently delivered articulation of the issues and themes conservatives have been stressing in the Obama era.

Santorum sniffed at “the politicization of science they call global warming,” blasted Obama’s healthcare reform law for killing freedom, promoted “supply-side economics for the working man,” and spent considerable time on “foundational principles” — the culture war issues that have suddenly become prevalent in recent weeks. And he took some shots at Romney — “the person in Massachusetts who built the largest government-run healthcare system in the United States – someone who would simply give that issue away in the fall, give the issue away of government control of your health.”

Again, in many ways this was a thoroughly average address, remarks that an entry-level political consultant could have drawn up for a candidate trying to curry favor with Tea Party Republicans and separate himself from a slippery opponent with an extensive moderate-to-liberal paper trail. But it was remarkable because everyone else who’s emerged from the GOP pack to vie with Romney has been incapable of delivering anything like it. Perry couldn’t remember the words, Cain could recite one slogan and nothing else, and Gingrich — the supposedly world-class debater — was either unable or unwilling to communicate a basic conservative case for himself and against Romney when they shared the stage.

For Romney, this is the real threat of Santorum’s candidacy: that for the first time a main challenger has emerged who lacks substantial personal and ethical baggage, whose policy views are largely consistent and in-line with those of the GOP base, and who is a competent communicator. If this sounds like a low standard, it is — and it says a lot about the 2012 GOP field that it’s taken this long for someone with such basic attributes to emerge (and that that someone is the guy who came to the race fresh off an 18-point reelection loss in a swing state).

Romney spoke about two hours after Santorum on Friday. His speech was also a competent expression of conservative grievances with Obama — “the poster child for arrogant government,” as Romney called him. But the message that Republican voters have been sending for more than a year now, in polls and in primary results like the ones we saw this week, is that they wonder if Romney really means it and that they’d prefer to have someone else representing them in the fall campaign. So it was probably not accidental that Santorum began his remarks by reminding the crowd that he’d been coming to CPAC for years — not just after he decided to run for president.

“I know you, and you know me,” he said. “And that’s important.”

On CNN this morning, Sen. Jim DeMint said that the GOP race “could very well go to the convention,” while former RNC Chairman Michael Steele on MSNBC pegged the chances of a deadlock at “52-48.” Sean Trende of RealClearPolitics makes a solid case for why they could be right. The basic idea is that there seem to be clear geographic and cultural divisions in the results so far — with Mitt Romney doing well in the Northeast and West, Santorum cleaning up in the Midwest, and Newt Gingrich faring well in the Bible Belt. If those divisions persist and Ron Paul manages to gobble up a chunk of delegates, the primary season just might fail to produce a clear winner.

But as fun as the scenario is to imagine, there’s a good reason to be skeptical of the deadlocked convention talk: We’ve heard it many times before in the modern campaign era, without anything ever coming of it.

The last time there was true post-primary season suspense on the GOP side was in 1976, when Gerald Ford and Ronald Reagan both emerged from the last wave of contests in early June short of the magic delegate number. But there were still a number of state conventions scheduled before the August national convention in Kansas City, and because it was a genuine two-man race, there was never any doubt that someone would win a first ballot nomination. Still, the drama in Kansas City was real, with Reagan trying to expand his support by anointing Pennsylvania moderate Richard Schweicker as his running mate — a move that unsettled conservatives and helped Ford secure a 1,187-1,070 victory on the first ballot.

That was the last truly unpredictable convention that either party has staged. But at various moments in primary campaigns since then, we’ve heard the kind of deadlocked convention chatter we’re now hearing. Here’s a look at our brushes with convention excitement:

1976, Democrats: This was the race that changed the way the political world understood the nominating process. As the Democratic race began, it was a common assumption that there would be a deadlocked convention, which is why there was no rush to crown Jimmy Carter as the inevitable nominee despite his weekly victories in primary states — and why two candidates, Idaho Sen. Frank Church and California Gov. Jerry Brown, both felt comfortable entering the race months after the first primaries began. And when Church and Brown enjoyed immediate success, it only strengthened the view that the Democratic convention would turn to a non-Carter candidate — maybe someone in the race already, or maybe Ted Kennedy or Hubert Humphrey. This was how Democrats were used to doing business. But the primary season had been radically expanded under new party rules, and when he won Ohio in June, Carter claimed to have a delegate majority. It steadily dawned on party leaders that he was right and that there’d be no deadlocked convention.

1980, Republicans: Reagan entered as the clear favorite, but there was considerable trepidation among party leaders (and the GOP’s then-vibrant moderate/liberal wing) about his general election prospects; his far-right rhetoric called to mind Barry Goldwater, who just 16 years earlier had suffered an epic defeat against LBJ. Reagan was upset by George H.W. Bush (who ran as the moderate wing’s candidate) in Iowa, recovered in New Hampshire, then struggled in a series of contests in New England — where liberal Republican John Anderson fared surprisingly well. This stirred talk of a deadlocked convention — one in which former President Ford, then seen as the party’s most bankable national face, would either play the role of savior or kingmaker. Here’s how Godfrey Sperling presented the Anderson and Ford scenarios in a March 1980 Christian Science Monitor column:

Just off his “impossible dream” in New England — and with his new momentum, Representative Anderson wins in his home state on March 18 and follows that by picking up enough crossover votes to take the Wisconsin primary on April 1.

Mr. Anderson then finally gets to the national convention with about 400 delegates, but with Messrs. Reagan and Bush deadlocked and Gerald Ford, now in the contest, having only enough votes to help another but not himself.

At that point, Mr. Ford gives his support to his old friend and sidekick in Congress, John Anderson, who marches toward the 998 delegates he needs for the nomination.

[SNIP]

With the current inability of any one candidate to take command, former President Ford may well decide to get into the race — even though he has already missed the opportunity to enter more than half of the primaries.

The Ford rationale is one in which he gets enough delegates to become the beneficiary of a deadlock at the convention.

But if Mr. Ford could “decide” the nomination by turning his delegates over to another, would his choice be Congressman Anderson? The former President is also a very close friend of George Bush.

But none of this ever materialized. Soon thereafter, Reagan won a solid victory in Illinois that sidelined Anderson (who then bolted the party to run as an independent), rolled it into the next wave of states, survived a surprise Bush win in Pennsylvania, and cruised to the nomination with a massive delegate majority.

1980, Democrats: This was essentially a two-man race between Carter and Kennedy, with Brown making some early noise but amassing few delegates. So, as with Reagan and Ford in ’76, it was clear the race would be settled on the first ballot at the convention — and Carter, boosted by the rally-around-the-flag effect of the Iran hostage crisis, emerged from the primary season with a clear majority. But Kennedy had closed strongly and Carter’s poll numbers were declining. So Kennedy made a last-minute push to change the convention rules and free delegates from their commitments. It was a long shot, but it provided for at least some suspense at Madison Square Garden. When it was rejected, the race was officially over.

1984, Democrats: The primary season opened with expectations that Walter Mondale would wrap up the nomination in record time. Instead, Gary Hart scored a surprise (if very distant) second place finish in Iowa, rolled it into a shocking New Hampshire win a week later, and soon had Mondale on the ropes. But Mondale bounced back with some key Southern wins, and the two men spent the spring traveling the country and trading wins — with a third candidate Jesse Jackson, picking up a few hundred delegates of his own. A deadlock seemed possible, as this Joseph C. Harsch column from March ’84 made clear:

There is now a visible chance that Mr. Mondale will not get a first-ballot nomination. If the delegates committed to Gary Hart and Jesse Jackson, and the uncommitted delegates, should pool their resources, they might be able to head off a quick Mondale victory. If so, then what happens?

The Democratic convention could at that point be blown wide open. Almost anything could happen. Suppose a lot of delegates are by that time disenchanted with the three existing candidates and start looking around for a possible alternative. One already hears talk of Sen. Dale Bumpers of Arkansas or Gov. Mario Cuomo of New York. Both are mentioned as possible running mates for Walter Mondale, but also as possible alternatives for the top of the ticket

But when the final primaries were over in June, Mondale declared himself the winner, thanks to strong support from a newly created class of convention participants — the superdelegates. (It also helped Mondale that party rules at the time awarded Jackson a small number of delegates relative to his strength in many states.) But Hart refused to quit. “Welcome to overtime,” he declared the morning after the last June primaries. He spent the next five weeks pointing to polls that showed him running better against Reagan than Mondale and pleading with superdelegates to change their minds, but they wouldn’t budge, and when the convention opened it was obvious Mondale would win on the first ballot.

1988, Democrats: It looked like Democrats had an epic mess on their hands when Jesse Jackson unexpectedly crushed Michael Dukakis in the March 26 Michigan caucuses — a result that put Jackson in the lead in the national delegate count. Dukakis was a weak  (accidental, really) front-runner, and by that point several other candidates and former candidates (Paul Simon, Dick Gephardt, Al Gore) were sitting on piles of delegates. Suddenly, it seemed like Jackson — who was demonstrating surprising support among white voters — might parlay his Michigan triumph into more victories and emerge from the primary season with the most delegates (but not enough for a first ballot nomination). From R.W. Apple Jr.’s March 29, 1988, New York Times story:

Democratic Party leaders expressed astonishment today at the Rev. Jesse Jackson’s landslide victory in the Michigan caucuses Saturday and confessed that they found it hard, after weeks of surprises, to predict how or when the party’s Presidential race would be decided.

For the first time, party professionals began actively contemplating the possibility that Mr. Jackson could emerge from the primary season, which ends in California and New Jersey June 7, with the most delegates.

One said that it was ”remotely, barely, distantly conceivable” that the party might actually end up by nominating Mr. Jackson. Others agreed that outcome was possible but, although they would not say it for attribution, almost none believed that a black candidate can be elected.

Paul Maslin, a highly regarded Democratic poll taker in Washington, commented: ”The party is up against an extraordinary end-game. If this guy has more convention votes than anyone else, how can we not nominate him? But how can we nominate him?”

It turned out they had nothing to fear. Party leaders closed ranks around Dukakis, who quickly beat Jackson in Connecticut, Wisconsin and New York, then rolled through the rest of the primaries without breaking a sweat.

1992, Democrats: Bill Clinton seemed to have the nomination wrapped up when he posted giant wins in Illinois and Michigan in the middle of March — this a week after Clinton had racked up a big delegate lead with a series of Super Tuesday wins. When his chief rival, Paul Tsongas, then suspended his campaign, the race seemed over. And then, out of nowhere, Jerry Brown won Connecticut, stunning Clinton in what remains one of the biggest primary season upsets ever. The result sparked genuine panic among Democratic leaders: Clinton had already weathered several scandals (Gennifer Flowers, Vietnam) and it was widely believed that Republicans would (in the words of Bob Kerrey) open him up “like a soft peanut” in the fall. The Connecticut result prompted some loud and public soul-searching: Is there anything we can do to stop this guy?

This set up the next contest, in New York, as a pivotal test for Clinton: Win and his campaign would be back on track; but lose again, and the floodgates might open. Already, names of potential white knight candidates (Mario Cuomo? Bill Bradley?) were being circulated, and Tsongas put out the word that he’d reenter the fray if Clinton lost again. Here’s how David Von Drehle summed it up in the Washington Post:

Yet while the Republicans are busy closing ranks around a candidate they despise in great numbers, the Democrats are furiously ripping the wings, legs and antennae from a front-runner they feel, well, squeamish about. They are unable to produce, halfway through the primary season, anything more than a crippled front-runner, an empty chameleon and sad hopes of a brokered convention.

But Clinton then won New York, and that was that.

1996, Republicans: There was a very brief window of deadlock talk after Bob Dole lost to Pat Buchanan in New Hampshire, casting doubt on Dole’s viability. But Buchanan was an unacceptable choice for most party leaders, which gave Lamar Alexander (who finished just behind Dole in New Hampshire) hope of emerging as the establishment’s preferred vehicle to take down Buchanan. But Steve Forbes, who was pouring tens of millions of his own dollars into the race, also hoped to play that role — and gained new credibility with wins in Delaware and Arizona after New Hampshire. The muddled picture that all of this created led to this kind of talk, captured in a New York Times story from late-February ’96:

Another possible result is that every victory by a candidate in one state will be canceled out by another candidate’s win somewhere else, and no candidate will amass enough delegates to avoid a brokered convention in San Diego in August.

“The scenario that’s emerging is the one that says, gee, maybe we’ll be deadlocked in San Diego,” said Mr. Ginsberg, the former Republican Committee official.

“That’s the one that captures the imagination. Deep in our heart of hearts, all of us would love to live through a brokered convention.”

Dole then won South Carolina by a convincing margin, killing Buchanan’s momentum and marginalizing the rest of the field once and for all. The Dole/Buchanan race that ensued wasn’t much of a contest.

2008, Republicans: Deadlock talk seemed sensible as the ’08 primary season opened; five candidates — Romney, John McCain, Mike Huckabee, Fred Thompson and Rudy Giuliani — were all bunched together in national polls, and all sorts of outcomes were plausible. Writing in the Boston Globe, Republican strategist Todd Domke summed it up this way:

If five candidates each win a fraction of delegates – 5 percent, 10 percent, 20 percent, 30 percent, 35 percent – there could be a deadlocked convention.

That would be like the GOP convention of 1860, when there were many factional, regional favorites. After three ballots, they settled on an Illinois attorney named Lincoln, a local “favorite son” since the convention was in Chicago. Once elected, he tried to achieve national and party unity by appointing his defeated foes to the cabinet.

We won’t be electing a political genius this time, but the campaign will be historic. And we best savor it by taking it seriously and humorously – as Lincoln once did.

But when January ended with McCain wins in South Carolina and Florida, the deadlock talk quieted.