Aug. 10 (Bloomberg) -- Iowa Republicans start winnowing the field of presidential contenders at an informal straw poll in Ames tomorrow, a day of reckoning that has dashed the ambitions of many would-be presidents in its 28-year history.

``I've said all along that if I don't come in first or second, I'll drop out of the race,'' said Tommy Thompson, a former governor of Wisconsin and Bush administration Cabinet official.

Part political rally, part summer festival, part fund- raiser, the event on the campus of Iowa State University won't award any of the delegates that will determine the 2008 Republican presidential nominee. Nonetheless, it gives an early indication of Iowa Republican sentiment before the state caucuses traditionally held in January, mainly by determining who leaves the stage.

``It's a peasant-maker, not a king-maker,'' said Chris Hull, who teaches polling and politics at Georgetown University in Washington and has written a book on the Iowa caucuses.

The stakes are highest for second-tier candidates such as Thompson, Kansas Senator Sam Brownback and former Arkansas Governor Mike Huckabee. This year's straw poll is largely a race for place and show, with former Massachusetts Governor Mitt Romney the presumed winner.

Romney's task is simplified by having no competition at the top. His two closest rivals among the current Republican candidates, former New York City Mayor Rudy Giuliani and Senator John McCain of Arizona aren't participating, dismissing Ames as nothing more than a fund-raising scheme for the state party.

`Waste of Money'

``It's a waste of money,'' Giuliani, 63, said when asked at a campaign event in Bettendorf, Iowa, why he wasn't taking part.

Another potential competitor, Fred Thompson, a former senator from Tennessee, hasn't officially declared his candidacy and won't have a presence in Ames.

Giuliani, McCain, 70, and Fred Thompson, 64, all trail Romney in most polls of Iowa Republicans.

Among the rest of the field, Romney has a distinct advantage in cash and organization, having raised the most money among all the Republican presidential candidates this year. The money helped Romney blanket Iowa with advertising. It also will buy plenty of the $35 tickets needed for each supporter to vote and pay for buses to get them to Ames.

Campaigns Gone By

The fields of Ames, smack in the middle of the state, are littered with the debris of presidential campaigns. Days after the 1999 contest, Republican Senators Elizabeth Dole and Lamar Alexander and former Vice President Dan Quayle all ended their quests.

For the candidates competing behind Romney, their intention is to ride a respectable showing in the straw poll, where roughly a third of caucus-goers participate, to the actual event near the start of the year. The reality is that Ames forces campaigns to re-evaluate their rationale for existing.

``It's like power-lifting,'' Brownback, 50, said. ``You get your strength from your legs in the straw poll and then you power on through to the caucus.'' Declining to predict how he would do, he said he will make an ``assessment'' after the ballots are counted tomorrow night.

Analysts and campaign advisers say there won't be nine Republicans in the race when the field leaves Ames.

``The only thing for certain is that there will be fewer candidates next week than there are this week,'' John Saltsman, Huckabee's campaign manager, said.

Moving On

A strong showing in Ames doesn't guarantee success in the delegate-selection caucus, traditionally the first contest in the presidential nomination race. In 1996, for example, then- Senator Phil Gramm of Texas tied fellow Senator Bob Dole of Kansas in the straw poll, only to finish fifth at the caucus in January. Dole went on to win the Republican nomination.

In 1979, George H.W. Bush, the president's father, won the straw poll, only to lose the nomination to Ronald Reagan, who went on to win the presidency.

Even Iowa Republicans have some doubts about the poll's accuracy as a predictor. The Iowa Republican Party asks activists on its Web page: ``Will the Straw Poll be an accurate indicator of who will win the Iowa Caucus?'' Forty-four percent of respondents voted no.

Then there are the candidates who running on issues more than their electoral viability. The three House members competing -- Representatives Duncan Hunter of California, Ron Paul of Texas and Tom Tancredo of Colorado -- have vowed to stay in the race, regardless of their results at Ames.

`Man on a Mission'

Tancredo, for example, has made border security and cracking down on immigration his cause. ``Tancredo is a man on a mission,'' Hull, the Georgetown professor, said. ``His funding does not come from electability, it comes from ideology.''

This year's contest is unusual because only one of the best-funded candidates is staking a claim on Ames, said Dennis Goldford, a politics professor at Drake University in Des Moines.

``We have a first-tier candidate in Romney, with lots of money, competing against a bunch of second-tiered candidates without much money,'' he said. ``It's like the 1980 Olympics when the U.S. didn't compete. Those gold medals mean less.''

To contact the reporter on this story: Hans Nichols in Ames, Iowa, at Hnichols2@bloomberg.net.

Last Updated: August 10, 2007 00:11 EDT