But most GOP primary voters probably didn’t know this. Fischer came to the race with little money or name recognition and spent virtually all of the campaign toiling the shadows of her two better-known opponents. The Palin endorsement came just a week before the primary, giving Fischer a sudden jolt at just the right time. It may be that all Republican voters really knew about her was that she was a rancher and a conservative (per the ads she ran), that she had Palin’s support, and that she wasn’t her rivals. And that was enough to pull out a victory that no one saw coming.

So even if Fischer isn’t a classic Tea Party conservative, she still managed to tap into the same basic aversion to establishment figures and appetite for outsiders that has produced some seismic GOP primary upsets in the Tea Party-era. And the fact that it comes just a week after six-term Senator Richard Lugar was crushed by 20 points in an Indiana primary underscores how severely the power of Republican incumbents and establishment heavyweights to beat back primary challenges has been reduced.

There could be some more Nebraska-like upsets in Senate primaries this year, but no other sitting senator is expected to be denied re-nomination as Lugar was. But 2014, when 13 more Republican senators are due to face the voters, could be a different story. After 2010, when primary season chaos derailed the GOP’s hopes of winning back the Senate, there was hope among the party’s establishment that the base’s restiveness would die down and that order would be restored. That hasn’t happened, obviously, so it’s probably time to look at which Republican senators should be – and probably are – sweating the most about ’14:

Lindsey Graham (South Carolina): Graham, a long-time irritant to national conservative leaders, is the face of the compromise-friendly approach to governing that the GOP base is revolting against. And South Carolina is arguably ground zero for the Tea Party revolt, home of Sen. Jim DeMint and the “four horsemen” quartet of true believer House freshmen. Any of them could be a viable primary foe against Graham (and one of them, Trey Gowdy, already beat an incumbent, then-Rep. Bob Inglis, by 42 points in a 2010 primary). Graham has said he expects to get a primary challenge, which seems inarguable.

Saxby Chambliss (Georgia): Chambliss, too, says he expects a primary. His voting record is reliably conservative (a career mark of over 90 percent from the ACU), but he was part of the bipartisan Gang of 6 deficit reduction negotiations last year and argued that tax increases had “to be part of the mix.”

Lamar Alexander (Tennessee): His reputation as a moderate has never quite matched up with his voting record, but the 71-year-old Alexander seems cut from the same cloth as Lugar – collegial manner, lots of talk of cooperation with the other side, occasional breaks with party orthodoxy, and a voting record that’s reliably Republican overall. But his age, his image, and his decades in state and national politics (he was governor from 1979 to 1987 and ran for president in 1996 and 2000) make him particularly vulnerable to an anti-establishment uprising. Alexander could take some consolation from the fact that his fellow Tennessee senator, Bob Corker, escaped a serious primary challenge this year.

Mitch McConnell (Kentucky): One of McConnell’s biggest humiliations came in 2010, when he threw his vaunted home state political operation behind Trey Grayson, only to watch his protégé lose the GOP Senate primary to Rand Paul. A five-term incumbent, the 70-year-old McConnell reeks of Washington insiderdom, so there’s plenty of speculation that he’ll be a primary season target. But there’s good news for McConnell: Paul is now on board with his ’14 reelection effort, and other veterans of Paul’s ’10 campaign are sending similar signals. For now, McConnell seems to be in good shape, but as the Senate’s GOP leader, there’s always a chance his fingerprints will end up on a legislative compromise that infuriates the base.

Pat Roberts (Kansas): He’s old (76) and has been on Capitol Hill for 32 years – the first 16 in the House and the last 16 in the Senate. He’s also a quiet, behind-the-scenes player whose voting record is only now evolving to synch up with the GOP base’s prevailing mood. It wouldn’t be too hard for an opponent to portray Roberts as a tired insider with Potomac Fever. Plus, the Kansas Republican Party is unusually prone to civil war. Roberts could provide an inviting target for, say, Kris Kobach, the youthful Kansas secretary of state who has become the leading national voice of the anti-immigration right.

Thad Cochran (Mississippi): This marks Cochran’s 40^th year in Congress. He was elected to the House in 1972, then replaced James Eastland in the Senate in 1978. At the time, Cochran was a trailblazer, the first Republican since Reconstruction to win a statewide race in Mississippi. But the post-civil rights migration of southern white voters to the GOP is now complete, and today Cochran is one of many. If anything, he hasn’t kept pace, with a voting record that’s not quite as conservative as where his party is. A bigger problem, though, could be Cochran’s fondness for earmarks, a key marker of insider-ness in today’s GOP. Cochran might be higher on this list if it weren’t for his weak fundraising and noncommittal answers about running again – strong hints that he’ll end up calling it a career at 77 years old.

Susan Collins (Maine): Collins’ voting record places her decidedly to the left of her GOP colleagues and Maine was home to one of the Tea Party’s signature 2010 triumphs – Paul LePage’s out-of-nowhere gubernatorial primary win (which was followed up by a narrow November victory). Collins, who was first elected in 1996, could be vulnerable if a challenger emerges, but it’s not clear one will – just consider the failure of the grassroots to mobilize against Olympia Snowe before Snowe’s unexpected retirement announcement earlier this year. Plus, Maine loves independents – it’s elected two of them governor since the 1970s, nearly anointed a third in 2010, and is on its way to sending one (Angus King) to the Senate this year. Collins may have the same insurance policy that was always there for Snowe: If things get too rough in her own party, the option of an independent bid will be there.

Obviously, this is a preliminary and speculative list. Some of these Republicans may end up coasting in 2014, and others who aren’t mentioned could find themselves in unforeseen peril.

What’s really worth watching is how the fear of a primary challenge weighs on all of their actions in the Senate going forward. How many of them will mimic Orrin Hatch – who was so spooked by the ’10 defeat of his fellow Utah Republican, Bob Bennett, that he reinvented himself as an abrasive, compromise-hating partisan warrior? Hatch’s primary is in six weeks – and he’s expected to survive.

In this narrative, the GOP didn’t mismanage the economy into the deepest downturn since the Great Depression. Rather, the economic crisis simply happened, ex nihilo, and Obama did nothing to stop or mitigate it. What’s more, he made things worse, with government spending and an explosion of debt.

The problem for Obama, as Bouie points out, is that there’s real appeal to this story. The electorate tends to exist perpetually in the present tense, with little collective memory or foresight. Republicans began banking on this the moment Obama was sworn in: Just stand against everything he’s doing, and if the economy remains in rough shape, sooner or later the public will hold him responsible, just because he’s the guy in charge. As it turned out, it took only about nine months for Obama’s approval rating to fall under the 50 percent mark, and it’s hovered around there ever since, putting him in danger of losing this fall.

One way the Obama campaign is attempting to counteract this is by challenging Romney’s own economic and job-creation credentials. The presumptive GOP nominee has been relentlessly touting his business (and not government) experience, hoping that voters will assume he knows how to fix the economy because of his private sector success. Polls suggest voters are buying it, at least to a degree, with Romney generally outpacing the president by several points on which candidate would be better on creating jobs and boosting the economy. This is the reason Obama’s campaign unveiled a brutal two-minute attack ad yesterday on Romney and Bain Capital on Monday; the idea is to convince voters that there’s not necessarily a connection between making money in business and understanding how the economy works.

It’s hard to say whether this will work. Romney is fighting back by highlighting jobs that were created through Bain and with a new video that tells the stories of struggling Americans who have been victimized by “the Obama economy.” As Greg Sargent explains, the video is a perfect reflection of both the misleading simplicity of Romney’s message and its potential effectiveness. There’s just a lot the Romney campaign can say and do to deflect from the impact of the Bain attacks.

In this way, Bush’s very brief reemergence today raises the question of whether Obama ought to be invoking his predecessor more frequently and more explicitly, and to make him a more central figure in the campaign. Polls show that voters still remember what happened on Bush’s watch and still hold him responsible for at least some of the country’s current problems. Obama does frequently make reference to what he inherited, and to the failure of the GOP to come up with a new economic platform during its White House exile. But more than anything else, it seems that Romney’s campaign fears being tied to Bush. And Bush, as his elevator trick shows, is willing to help them out by remaining inconspicuous. If Obama’s team wants it, there’s some slack to be picked up.

But outside of that ’94 primary, every time Romney has been in a competitive race, an opponent has accused him of making his fortune by gutting companies and ruining the lives of innocent workers.

The new Obama ad, which is airing in Virginia, Pennsylvania and Colorado, focuses on the story of GST Steel, a company in which Bain purchased a majority stake in 1993, just before Romney’s first foray into politics. In 2001, after Romney had left his day-to-day role with Bain and was overseeing the Olympics in Utah, GST’s Kansas City plant was shuttered, costing more than 700 workers their jobs even as Bain itself profited. The ad mixes in clips of Romney boasting about his job creation record and empathy for the jobless with testimonials from those whose lives were affected by the plant’s closure.

“It was like a vampire,” one former GST employee says of Bain. “It came in and sucked the life out of us.”

It’s a dramatic, well-produced ad that paints a damning portrait of the presumptive GOP nominee and the firm he built. The question is whether it will be effective, and the track record for previous Bain assaults on Romney is mixed:

1994 Senate general election: Here is the example the Obama team is hoping to emulate. After his September ’94 GOP primary win, a poll gave Romney a narrow edge over Ted Kennedy, whose own popularity had waned in the wake of the William Kennedy Smith trial. By the end of the month, the Kennedy campaign settled on Bain as Romney’s prime vulnerability, and made the firm’s acquisition of an Indiana company, SCM, a major point of emphasis. Here is one of several SCM ads that Kennedy’s campaign ran:

Interestingly, when this assault began, the Boston Globe noted that Romney had been running warm and fuzzy ads about his personal story for a few months and suggested that “voters may see this series as the powerful Kennedy machine beating up on that nice young man.” But by early October, Kennedy was comfortably ahead again, and the race wasn’t close the rest of the way, with the incumbent prevailing by 17 points. Were the Bain spots responsible for the giant polling shift? It’s impossible to say for sure, but they clearly didn’t hurt.

2002 gubernatorial general election: Romney spent much of the fall campaign running behind the Democratic nominee, state Treasurer Shannon O’Brien. He seemed to gain traction, though, with an attack ad that played up the losses that the state’s pension fund incurred on O’Brien’s watch from investments in Enron.

O’Brien countered by reviving the SCM story, running ads on the incident and calling Romney “the face of corporate greed in America.” She also launched an spot called “Sizzle” that featured a laid-off worker from GST – the same steel company Obama is now highlighting – who told viewers:

“It’s hard to believe that a man like Mitt Romney can have enough power and influence and money behind him to come in, destroy families, put people out of work that’s sick, with no health insurance. There’s nothing left. We have nothing left.”

O’Brien, though, lost to Romney by 7 points. This doesn’t mean the Bain attacks backfired. As Boston journalist Dan Kennedy noted today, Romney struggled throughout the ’02 general election more than the prior two GOP candidates – Paul Cellucci and Bill Weld – had. And it may have been a last-minute push by Romney to link O’Brien to unpopular Democratic leaders in the state Legislature that moved voters. Still, the fact remains that O’Brien played the Bain card aggressively, and it didn’t bring her to victory.

2008 Republican primaries: Bain was not a huge issue in this race, but when Mike Huckabee said that Romney reminds people of “the guy who laid you off,” he was clearly trying to harness the instinctively negative feelings that even many blue-collar Republicans have toward the world of venture capital. That line may have helped Huckabee in Iowa, where he beat Romney by 9 points.

Then, in the run-up to Florida’s primary, John McCain directly attacked Romney over Bain, arguing that “as head of his investment company he presided over the acquisition of companies that laid off thousands of workers.” McCain ended up winning Florida narrowly, a result that cemented him as the clear front-runner and dealt a severe blow to Romney’s hopes.

2012 Republican primaries: The attacks on Bain were far more pointed in Romney’s second bid for the GOP nomination, with Rick Perry accusing him of practicing “vulture capitalism” and Newt Gingrich branding him a “predatory corporate raider.” The Gingrich campaign even created a vicious 29-minute video titled “King of Bain,” which was released about a week before the South Carolina primary:

Democrats, of course, were delighted by this development, and an income gap came to define the GOP race, with Romney generally cleaning up with affluent Republicans voters but often losing to Gingrich (and later Rick Santorum) with those in the working and middle classes. At the same time, Gingrich took immense heat from leading Republican voices, who blasted him for doing dirty work for Democrats and defended Romney’s Bain work. And Santorum refused to join the Bain pile-on, saying that “I just don’t think as a conservative and someone who believes in business that we should be out there playing the games that the Democrats play, saying somehow capitalism is bad.”

What the Paul crowd can do, though, is make noise – loud, uncontrollable noise that disrupts the proceedings and gives the media something to play up. Exhibit A: The headline from the Arizona Republic’s story about Saturday’s convention: “Arizona Ron Paul supporters boo Romney’s son off stage.”

There’s some dispute over the accuracy of that headline, which was mimicked by leading national publications. According to the Republic’s report, Josh Romney, who was representing his father’s campaign at the convention, “had to stop repeatedly as people booed and yelled for Paul.” But some Paul supporters say Romney was only jeered when he encouraged attendees to support his father’s slate and that he wasn’t forced to leave the stage. The video that’s available doesn’t clear things up.

Not that it really matters: Whether it was over and over again or just once, the bottom line is that Paul’s crowd loudly booed the son of their party’s presumptive nominee. And it’s hardly the first time something like this has happened at a state convention. When they seized control of Alaska’s convention last month, for instance, pro-Paul attendees heckled two United States senators, Lisa Murkowski and John Barrasso, who were there to speak. That too made national news.

Similar behavior by Paul backers in Tampa could spoil what for the Romney campaign is supposed to be a nationally televised infomercial. The problem for Romney and convention organizers is that, short of giving up and letting Ron Paul have the nomination, there’s not much they can do to pacify the Paul-ites.

Under the extreme worst-case scenario for Republicans, Paul supporters end up with a giant share of the delegate slots (a quarter of them, say) and launch a four-day heckle-fest, bitterly resist any effort to quiet them or evict them from the hall – a modern version of the chaos that reigned inside Chicago Stadium Chicago’s International Ampitheatre at the Democrats’ 1968 convention. In a more optimistic scenario, there’s only limited booing from a handful of delegates, and it rates on the nuisance scale somewhere near the annoying air horns that were a little too audible during Ronald Reagan’s 1980 acceptance speech in Detroit.

The good news for Republicans is that Paul himself will have an incentive to help them, since he’s interested in his son Rand’s long-term political viability and probably won’t want the family name forever associated with a destructive national convention. So if his supporters get too exuberant in Tampa, Paul might simply express to them how important he believes it is that they treat speakers with respect – sort of like when a rowdy crowd at a sporting event starts to disrupt the game and the home team’s coach steps in to quiet them down. Here’s former Cincinnati Bengals coach Sam Wyche with a lesson in how it’s done:

Those last three words are the key. The bill to strip public employees of their right to bargain collectively was introduced a few weeks after Walker’s chat with Hendricks, prompting protests of an unprecedented scale in Madison and giving rise to the recall effort. Walker has long argued that he was responding to a budgetary emergency, and that unduly generous contracts won by public sector unions were a big reason for it. His desire, the line goes, was merely to correct a flawed system that encouraged elected officials to commit huge sums of taxpayer money to public employees, for fear of incurring their wrath in elections.

What Walker swears he wasn’t – and isn’t – interested in doing is taking power away from private sector unions. There’s a very practical reason for this. In Wisconsin, an unusually large segment of the electorate – 26 percent, in the most recent statewide election — is composed of voters from union households. (Nationally, the figure is 17 percent.) And the union tradition is ingrained in the state’s history. So Walker, in his public comments, routinely distinguishes between the two types of unions. “Private sector unions,” he said recently, “have been our partner in the economic revival we’ve had in this state. A bigger issue is the impact the public-sector unions have had on the taxpayers.”

Union leaders and their Democratic allies have been pleading with voters to see this as a ruse, a way for Walker to divide the union movement by pitting public employees against private sector workers. Which makes the new video so powerful. Here is the governor conversing with a billionaire (who later gave $500,000 to his campaign) and telling her all about his “divide and conquer” strategy against union power. Granted, it’s not clear if Walker is actually laying out a road map to make Wisconsin a right-to-work state (a complete transcript of the exchange isn’t much help), but the video basically conveys everything that Democrats have been trying to get voters to see about him. And its run-time is 28 seconds – ready-made for a television ad.