Apparently the chance to appear in public with both President Bush and John McCain in one week isn’t as much of a draw as it used to be.

Most of the Republican candidates in this fall’s marquee Senate races are either skipping the GOP convention in St. Paul, Minn., or trying to duck questions about whether they’ll make it there or not, National Journal’s Erin McPike reports. That’s a sharp contrast from four years ago, when nearly any Republican running for statewide office anywhere not only flocked to New York for the party’s convention but scheduled as many fundraisers during the week as they could possibly cram into their days and nights. Alaska Sen. Ted Stevens, Maine Sen. Susan Collins and Wayne Schaeffer, who’s trying to hold a Colorado seat for the Republicans, have all ruled out attending. Incumbents Elizabeth Dole in North Carolina, Gordon Smith in Oregon, John Sununu in New Hampshire and Roger Wicker in Mississippi, as well as candidates John Kennedy in Louisiana and Steve Pearce in New Mexico, say they’re not sure whether they’ll be there.

None of the GOP candidates or their aides will say they’re skipping the convention because the party as a whole isn’t that popular with run-of-the-mill voters, of course. Stevens has to stay home for a primary that week (as does his Democratic opponent, Anchorage Mayor Mark Begich). Most of them say they just don’t have time to leave the campaign trail in their home states to go hobnob for a week.

But if you’re, say, Gordon Smith, trying to hold onto your seat in the state where a Barack Obama rally drew 75,000 people this spring, chances are you aren’t really looking forward to being part of daily features on the Oregon delegation to McCain’s convention in local newspapers around the state. (If you were, you probably wouldn’t have run a TV ad that tried to make voters think Obama had endorsed you.) Besides the chance to raise some money — and maybe commiserate with other endangered Republican incumbents — there isn’t much upside for GOP candidates in going to the convention.

This sort of thing isn’t unprecedented. Plenty of candidates don’t spend the entire week at their party’s convention — four years ago, then Senate Minority Leader Tom Daschle left Boston early to head back to South Dakota (and then ran a TV ad similar to Smith’s, featuring him hugging Bush, while the Republicans gathered a couple of weeks later). Still, even if candidates drop in for only a day or two, it can’t be a good sign for their campaign that they don’t feel like they can spend the entire week away from the trail. Most of the Democratic candidates in these races say they’ll definitely be going to Denver for Obama’s convention.