Exceed expectations, and receive reams of flattering national publicity. Disappoint, and watch campaign donations dry up overnight.
"A single bad performance in an actual caucus or a primary can be less devastating to a campaign than underperforming at the Iowa Straw Poll,'' said Gentry Collins, an Iowan and former political director at the Republican National Committee.
Just ask Lamar Alexander, Sam Brownback, Elizabeth Dole, Dan Quayle, and Tommy Thompson, all of whom bowed out of the race after weak showings in this quirky, quadrennial mock election.
Candidates with the most to win or lose this year include Bachmann, Pawlenty, Herman Cain, Ron Paul, and Santorum. Mitt Romney and Jon Huntsman aren't mobilizing supporters to go to the poll, but their names will appear on the ballot, and both will participate in the televised debate here on Thursday.
What started in 1979 as a fundraiser for the Iowa Republican Party has evolved into a mini-ground war, testing each campaign's grassroots operation in the state that will eventually host the first nominating contest. If you can persuade thousands of Iowans to trade their Saturday for a road trip to Ames in the dead of summer, the thinking goes, perhaps you are qualified to be the leader of the free world.
Though the straw poll inevitably shapes the road to the White House -- by determining who gets to stay the course -- history shows that it's an unreliable harbinger of future success. Only two of the past five straw poll winners have gone on to become the party nominee.
"It's been my experience, not just in my campaign but in previous campaigns, that the Iowa Straw Poll has a shelf life of about 24 hours,'' said the poll-shunning 2008 GOP nominee, Sen. John McCain of Arizona, in a recent interview at the Capitol. "It has minimal impact on the eventual outcome, as to who the nominee of the party is. It's a straw poll --and, at least in my experience, it doesn't necessarily reflect the views of all Republican voters.''
Despite polls showing that Perry will immediately become a top contender, his name will not be listed on the straw poll ballot. With the absence of a commanding front-runner, some Iowa Republicans are worried about a low turnout on Saturday. About 14,300 people participated in 2007, compared with about 24,000 in 1999.
"What bothers me is that this is Iowa's showcase, the greatest party and the largest gathering of Republicans outside a national convention,'' said Chuck Laudner, a former executive director of the state party. "For Iowans to sit on their hands and not blow the doors off this would be very disappointing.''
Here's a rundown of the stakes for each of the major players in the race:
Michele Bachmann: Her perch beside Romney at the top of the polls demands an equally strong finish on Saturday. Bachmann's challenge is to prove she can parlay national buzz into a solid ground game. A big turnout will likely benefit her. "My women in Iowa really like her, but this contest is all about who shows up,'' said Penny Nance, CEO of Concerned Women for America, a Christian conservative group. Bachmann has been emphasizing her roots in Waterloo, Iowa, support from religious leaders, and a never-surrender position on the debt ceiling.