Rick Santorum and Mitt Romney have finished in a virtual dead heat at the Iowa Republican Party caucuses.
The official declaration showed that Romney had beaten Santorum by just eight votes, each with 25% of the vote.
Texas Congressman Ron Paul finished third with 21%, followed by Newt Gingrich (13%) and Texas Governor Rick Perry (10%). Despite being an early front-runner in the race, Michele Bachmann finished with just 5%, while Jon Huntsman finished with 1%.
Perry said late on Tuesday that he would return to Texas to consider whether he would continue his campaign. Romney spoke to voters after the caucus, describing the result as a "campaign night where America wins". Romney also took the opportunity to attack Obama.
"Almost everything the President has done has made it harder for businesses to grow," Romney said.
Speaking before the final result was announced, Santorum thanked voters for their support.
"I've survived the challenges so far from the daily grace that comes from God," Santorum said after proclaiming "game on."
"Thank you so much Iowa," he continued. "You, you, by standing up and not compromising, by standing up and being bold and leading, leading with that burden and responsibility you have to be first, you have taken the first step of taking back this country."
The symbolic start of the presidential race, the Iowa primary, though never an anointing, traditionally forces the capitulation of candidates who poll poorly. Following a turnout of around 120,000, similar to the 2008 numbers, Tuesday's vote split the nominees into two tiers, with Santorum, Romney and Paul in the first tier, followed by Gingrich and Perry in the second tier.
Despite being born in the state, Bachmann, who came last (apart from Jon Huntsman who didn't campaign), is now effectively out of the race, particularly as her campaign coffers are reportedly empty. It's a surprising turnaround for Bachmann, who only last August won the Iowa Ames straw poll, albeit by a small margin.
The caucuses, a group of town hall-style meetings comprising speeches by surrogates of the candidates and a vote, encompassed around 17,000 sites in the Hawkeye State, with the campaign build-up to Tuesday's vote proving particularly brutal.
In the days and hours leading up to the polling, candidates lined up to offer broadsides against each other and President Obama.
Prior to the poll, Ron Paul's campaign launched an anti-Romney attack ad, a one-minute radio spot calling the former Massachusetts governor a "liberal" supportive of bank bailouts and healthcare legislation.
Reported by The Hill, Romney countered by arguing that he had become more conservative over the past decade. "That was 10 years ago, and I'm more conservative than I was 10 years ago," he said. "Having served as governor, having worked in a state where my legislature was 85% Democrat, having lived my life over those last 10 years, I've become a little more conservative over time."
Newt Gingrich joined the fun, scrambling for the evangelical vote by proclaiming he "wouldn't make exceptions" for abortions, even in cases of rape or incest.
Jon Huntsman, despite deciding to skip campaigning in Iowa (he is due to kick start his campaign in New Hampshire on 10 January), still had a few choice words for Romney, telling The Huffington Post that the former Massachusetts governor, if elected, would work as an agent for the much-despised big banks.
Elsewhere, Bachmann, never short of a questionable sound bite, used one of her last speeches before the vote to say that President Obama had treated America like "a third-world banana republic".
What does Tuesday's result mean? In 2008, Mike Huckabee won the Iowa Caucuses, with Mitt Romney coming in second. Yet it was John McCain that eventually won the nomination. Although Romney remains the most likely candidate to receive the 2012 Republican nomination, after four years of campaigning the 64-year-old has shown little improvement on his 2008 standing in the state.
For Gingrich and Perry, the result is enough to see them through to the next round of the contest, but there is very little to suggest that either's candidacy has legs. For Paul, the question remains as to whether he can use this good showing to expand his candidacy beyond his existing hugely loyal following.
The 76-year-old Libertarian remains unpopular within the traditional GOP, with Newt Gingrich using his post-result speech to highlight the "dangers" of Paul's foreign policy, specifically in regards to the Iranian nuclear question. Yet there is now little doubting that Paul's economic plan, allied to his desire to bring home American troops is striking a chord with a worried and war-weary citizenry, particularly among the young.
Yet the real winner appears to be Rick Santorum, who only weeks ago was polling in low single digit figures. However, following the Santorum surge and Tuesday's result, the cash-heavy Romney campaign is now likely to be crafting an attack strategy to sully the 53-year-old social conservative's record in a similar manner to the campaign Romney's team so effectively launched against Gingrich in recent weeks.