There's the local press, handshaking, baby-kissing, and sucking up to small town politicians. But that's probably not why GOP presidential candidate and former Pennsylvania Sen. Rick Santorum, who has consistently polled at about 2 percent since launching his bid, has visited all 99 counties in Iowa.
Just as the bad coffee, cheap hotels, and hassle of airport security probably are not reasons why Texas Rep. Ron Paul, who is expected to make a strong showing in the Iowa caucus but is polling at about 6 percent nationally, remains committed to the trail.
As last night's foreign policy debate showed, when you are polling below the margin of error and relegated to the debate stage periphery, it can be a thankless task to try and break through the noise of the top candidates.
So why do presidential candidates stay in the race long after their fate is obvious?
"It's hard to get up every day and campaign so you have to convince yourself that lightening could strike and is going to strike," says Stu Rothenberg, editor of The Rothenberg Report, a non-partisan campaign newsletter. "These people have invested months in the campaign and it's hard to just look in the mirror and say, 'well, I'm just not going to be president.'"
In this year's GOP presidential race there are several candidates whose campaigns never took off, including Santorum, former Utah Gov. Jon Huntsman and Texas congressman Ron Paul, and still others whose bids flamed out early, including Minnesota Rep. Michele Bachmann, Texas Gov. Rick Perry and Herman Cain. According to a recent national poll conducted by Quinnipiac University of likely Republican primary voters, each of those candidates is polling at about 6 percent or below, with the exception of Cain, who garnered 14 percent support but has lost the top spot after accusations of sexual harassment and gaffes on the campaign trail have soured voters' impression of him.
But in a race that has been a merry-go-round for candidates in the top slot, there are many reasons to stay in.
"After Michele Bachmann, Rick Perry, Herman Cain, Newt Gingrich all rise to the top of the polls, why wouldn't Ron Paul and Rick Santorum and Jon Huntsman think their chance is next?" asks Danny Hayes, a government professor at American University.
Kyle Kondik, political analyst at the University of Virginia's Center for Politics, agrees.
"There's just been an unsettled nature to the race in which even also-rans and long shot candidates like Santorum don't see anyone pulling away and so why not stay in the race as long as you can afford to do so?" he says. "I think that's why we haven't seen anyone drop out."
And with the exception of former Minnesota Gov. Tim Pawlenty, who dropped out of the race just after an Iowa straw poll earlier this year, candidates often stick around until at least the first primary ballots are cast. It was not until after the Iowa caucuses in 2008 that then-Sens. Joe Biden and Chris Dodd bailed out of the Democratic race. That same year, GOP nominees Fred Thompson and Rudy Giuliani did not drop out until after disappointing finishes in South Carolina and Florida, respectively.
Many lower-tier candidates commit to making "last stands" and rarely exit before those tallies are taken. This year, Bachmann and Santorum are banking on strong finishes in Iowa, for Huntsman it's New Hampshire, and South Carolina for the likes of Cain and Perry.
Serious motivations besides ego include candidates' desire to drive certain issues into the spotlight and yes, potential future monetary gain.
"I think sincerity does actually motivate politicians in many ways," says Hayes. "But it's also the case that being a prominent figure who is a leading voice for a cause can be beneficial for public figures and politicians down the line."
Candidates who prove to be champions for a specific cause can win friends with interest groups and organizations that pay dividends after the race is over, he says. Not to mention the fact that at least three candidates—Bachmann, Cain and former House Speaker Newt Gingrich—are all promoting new books while they are campaigning.
While staying in the hunt after the pack has left you behind could undercut a candidate's reputation, Hayes says there is one final, human motivation that makes it tough to drop out.
"It's very hard when people who are supporting you are telling you to keep going. People have given you money, they've donated their time, people have invested a lot in these candidates and so pulling up the stakes and going home isn't a decision that most of the candidates want to make on their own," he says.