Michele Bachmann won a test vote of Iowans on Saturday, a show of strength five months before the state's caucuses kick off the Republican presidential nominating season.

The result is the first indication of what Iowans think of the field of Republicans competing for the chance to challenge President Barack Obama in 2012. But it's hardly predictive of who will win the winter Iowa contest, much less the party nod or the White House.

Rather, Saturday's outcome suggests that the Minnesota congresswoman has a certain level of support and, perhaps even more important, the strongest get-out-the-vote operation and widest volunteer base in a state whose caucuses require those elements.

The poll provides clues about each candidate's level of support and campaign organization five months before the Iowa caucuses kick off the Republican primary season.

The results of the nonbinding vote, held on the Iowa State University campus, came just hours after Texas Gov. Rick Perry entered the race.

Political festival

"We are going to make Barack Obama a one-term president," Bachmann declared to cheers on the campus of Iowa State University during a daylong political festival. A few hours later, she learned she had won the poll and said: "This is the very first step toward taking back the White House."

The candidates on the ballot for the Republican straw poll in Iowa were, top row from left: Michele Bachmann, Herman Cain and Newt Gingrich; middle row from left: Jon Huntsman, Thaddeus McCotter and Ron Paul; bottom row from left: Tim Pawlenty, Mitt Romney and Rick Santorum. (Associated Press)Bachmann — the tea party favourite with a following among Christian evangelicals who make up the GOP base in Iowa and elsewhere — got more than 28 pe per cent of the 17,000 votes cast in the nonbinding exercise.

Texas congressman Ron Paul, who has support among libertarian-leaning voters, came in a close second. Tim Pawlenty was looking for a strong showing to boost his struggling campaign, but the former Minnesota governor finished a distant third, raising questions about the future of his candidacy.

"We have a lot more work to do," Pawlenty said, suggesting he wasn't dropping out despite the disappointing finish. "We are just beginning."

Rick Santorum, the former Pennsylvania senator, was fourth, followed by pizza tycoon Herman Cain.

Perry — who wasn't on the ballot but was written-in by supporters — came in sixth, just ahead of GOP front-runner Mitt Romney, the former Massachusetts governor who didn't compete in the straw poll.

Also on the ballot but barely registering support were Jon Huntsman, the former governor of Utah and more recently ambassador to China in the Obama administration, and Newt Gingrich of Georgia, the former House Speaker.

Candidates blast Obama

Despite Perry's best efforts to grab the spotlight, the epicentre of the presidential contest was Ames, Iowa, where about 17,000 voters cast ballots during the daylong political festival, a late-summer ritual held every four years.

In speeches throughout the day, candidates scouted for support by assailing Obama and offering themselves as the answer to an America plagued by high unemployment, rising debt and stock market swings.

"We know what America needs. But unfortunately Barack Obama has no clue. He's like a manure spreader in a windstorm," Pawlenty said, adding: "Mr. President, get the government off our backs."

Bachmann stressed her Iowa roots — she was born in Waterloo — as well as her faith, opposition to abortion rights and opposition to gay marriage.

The win by Bachmann, riding high since entering the race earlier this summer, bolstered her hopes of holding off Perry who will try to infringe on her base of tea party and evangelical support.

She invoked God and faith as she stressed what she called her conservative values, saying: "In Iowa, we are social conservatives and we will never be ashamed of being social conservatives."

Perry, Palin not on ballot

Perry and Sarah Palin, who made a splash Friday when she visited the state fair, weren't listed. But their backers planned write-in campaigns that could outpace candidates who have spent months trying to line up supporters to participate.

The straw poll isn't a scientific poll at all; it amounts to a popularity contest and a test of organizational strength. Poor showings usually force some candidates, mostly those who are not well-known and are struggling to raise money, to abandon their bids. That could happen this year, too.

The straw poll has a mixed record of predicting the outcome of the precinct caucuses.