|Bachmann's campaign received an early boost with the win in the straw poll, ahead of key primaries in Iowa [Reuters]
Republican Tim Pawlenty, a former Minnesota governor, has dropped out of the race for his party's US presidential nomination, just a day after finishing third in the Iowa straw poll.
Michele Bachmann, a congresswoman representing Minnesota's sixth district, won the poll with 28.5 per cent of the vote, edging out Libertarian congressman Ron Paul, who came in a close second. Pawlenty finished third in the poll.
"I'm going to be ending my campaign for president, but I'm very, very grateful for the people of Iowa, the people of this country, who I had a chance to make my case to, and for my supporters and staff and friends who've been so loyal and helpful," he told ABC television on Sunday.
"We needed to get some lift to continue on and to have a pathway forward. That didn't happen."
Pawlenty had struggled to gain traction in the state, which he had previously said he must win. He expressed his confidence, however, in his party's ability to nominate a candidate who could beat Barack Obama, the current US president, in the 2012 polls.
Pawlenty, who served two terms as Minnesota's governor, was on the vice-presidential short list for Senator John McCain's run at the White House in 2008.
He had hoped to have become an alternative to national front-running Republican candidate Mitt Romney, but unexpectedly found himself trading public verbal blows with Bachmann, who is a favourite of the Tea Party movement.
The former governor had struggled to raise money and connect with voters, and after failing to win the straw poll in Iowa, where he had spent a considerable amount of resources, he decided to call time on his bid for the presidency.
Bachmann wins poll
However, the win in Iowa provided an early boost to Bachmann's campaign for the White House.
She came out on top after campaigning hard in the heartland state, with 4,823 votes, or 28.5 per cent, of the 16,892 votes cast in the early test for Republicans.
Congressman Paul came in a close second with 4,671 votes, followed by Pawlenty in third with 2,293.
Saturday's result came five months before Iowa holds the caucuses that kick off the Republican nomination season.
Observers had pointed out that Pawlenty would have needed a sterling Iowa performance to maintain a healthy campaign.
Texas governor Rick Perry, who formally kicked off his campaign earlier on Saturday - leaping immediately near the head of the crowded field - was not in the running for the Ames poll, but still garnered 718 in write-in votes.
Perry's write-in tally was notably ahead of the other front-runner, former Massachusetts Governor Mitt Romney, who received only 567 nods - though he has not spent much time in Iowa, preferring to focus on other states.
John Nichols, a political writer for The Nation magazine, told Al Jazeera that it was "not entirely surprising that Bachmann won, seeing as she was considered the star of the Iowa polls, but it would come as unpleasant news for Pawlenty who staked an immense amount of effort and energy in doing well in these polls.
"This loss could actually knock him out of the race," Nichols had said, hours before Pawlenty made his announcement.
Explaining what he thought was the underlying message of polls, Nichols said: "These Republicans believe Barack Obama is vulnerable, so they are very serious about these races; spending tens of millions if not hundreds of millions.
"So they are not playing games here - this is not a family feud. This is a really serious fight to get the nomination."
Asked who he thought Obama could most easily beat at the polls, Nichols replied: "That guy is a girl - Michele Bachmann.
"They would love to run against Bachmann because they believe of all the candidates, she is the one that most frightens the middle. She seems too extreme.
"Between Perry and Romney it's a little more complex but they would fear Perry more because he is a sitting governor with a current record.
"As it happens, the Texas economy is a little bit better than the rest of the country; so they would prefer not to run against him and would see Romney as somewhat more vulnerable."
The Iowa poll is seen as a key early indicator for how Republican candidates will fare in the state's caucus early next year, and tends to favour conservative candidates who can electrify their activist base.