Two of the most important factors during a primary campaign are momentum and math — meaning how many delegates you've got.
What do you do when neither one of those things is running in your favor?
That's a question people are starting to ask about former Pennsylvania Sen. Rick Santorum — and have wondered about for a while now about former House Speaker Newt Gingrich and Texas Rep. Ron Paul.
Santorum (and the others) not only lost Wisconsin, Maryland and Washington, D.C. (where Santorum failed even to qualify for the ballot), on Tuesday, but gained only a handful of delegates.
It seems highly improbable that any of them will be able, at this point, to deny former Massachusetts Gov. Mitt Romney the Republican presidential nomination.
So why do they keep running?
"Why do hall of fame athletes have to wait until they get cut by their team before they call it quits?" says Henry Olsen, vice president of the American Enterprise Institute. "It's just entirely up to the psychology of the individual."
That may be so, but there appear to be several recurring reasons why, in nearly every election cycle, one or two candidates keep running long after the media and party officials have openly declared that it's past time for them to stop.
Lightning May Strike
There are plenty of politicians in office because they happened to be in the right place at the right time. Often that simply means being available when the presumptive favorite falls victim to scandal or some other unforeseen circumstance.
"Your chances of winning may be only 1 percent if you stay in the race, but they are zero percent if you drop out," says Larry Sabato, director of the University of Virginia Center for Politics. "They've all learned the Tim Pawlenty lesson — hang on for dear life, lest you miss your moment, or your second moment or your third one."
Pawlenty, a former Minnesota governor, dropped out of the GOP race last August after losing the Iowa straw poll — just as the Republican electorate was starting to pay attention and giving its polling support to new front-runners every few weeks or so.
Plenty of no-hopers in the past have won primaries long after their chances of winning the nomination were practically nil. There are still plenty of delegates to be won, and more delegates can translate into greater clout at the convention, leading to a better speaking spot or improved hopes of pet issues making it into the party platform.
Such a scenario has long been the conventional wisdom regarding Paul's strategy. But it may apply to the others at this point as well. A strong showing for Santorum in a big late state such as, say, Texas, which holds its primary on May 29, will lead to not only more delegates but a renewed round of media exposure.
For any candidate, a higher profile leads to better-paying speaking gigs and maybe a plum job as a pundit on TV.
It takes a lot of personal resolve to gear up for the grinding, privacy-destroying task of running for president. Once you believe the country would best be served by putting you in the Oval Office, it's hard to accept that it's not going to happen.
"Newt believes he has the best ideas, that he's the smartest guy and would make the best president," says Terry Madonna, director of the Center for Politics & Public Affairs at Franklin & Marshall College in Lancaster, Pa. "He's having a hard time accepting that not everyone sees it that way."
Madonna, a longtime Santorum watcher, says the former Pennsylvania senator may also be struggling with the idea. After all, he had been dismissed as a nonstarter as the year began owing to his low standing in the polls, only to emerge as Romney's leading challenger.
"Santorum is a man who genuinely believes that this is his moment in American history and that his views are essential to the salvation of the nation," Madonna says.
There's No Downside
Party elders may be calling on Santorum and the others to stand down and allow Romney to devote his resources and rhetoric to taking on President Obama. But there may not be much incentive for the trailing candidates to do so.
Gingrich and Paul have reached an age where running again is unlikely.
Santorum is just 53, but he may be calculating that it's smarter for his own future hopes to continue barnstorming the country and making new friends and alliances than stepping down in favor of Romney, AEI's Olsen suggests.
A candidate dismissed as having little chance of garnering the nomination won't receive the same kind of attention that someone still in the hunt would get. But he'll still get more than he would if he dropped out.
No one turns out to hear speeches by a noncandidate. Cable shows may still have you on, but they're going to ask you questions about the issues of the day, rather than about yourself.
"A presidential candidacy is addictive," Sabato says. "Inertia is the second most powerful force in the universe, right after gravity."