• Mitt Romney, Ron Paul and Rick Santorum riding high in polls
• Republican volunteers pour in from other states to offer help
Republican presidential candidates fanned out across Iowa on Monday in a final bid to corral voters ahead of Tuesday's caucuses, the first contest of the 2012 election.
Volunteers were pouring in from other states to help with the final push. Rick Perry's team said they had 500 volunteers joining them from more 30 states.
The candidates, up from early morning and preparing to campaign late into the night, spread themselves across Iowa, ready to clock up hundreds of miles on the final full day. Mitt Romney, the frontrunner in the polls, concentrated on areas he won in his failed bid in 2008, seeking to build on the 25% of the vote he secured then.
Given the fractured nature of the Republican field this time round, 25% may be enough to give Romney victory.
Polls show Romney, Texas senator Ron Paul and former Pennsylvania senator Rick Santorum all with a chance of securing the top spot. Santorum, the most socially conservative of the candidates and backed by Christian evangelical leaders, called on Iowans to create a "shockwave" on Tuesday night by selecting him.
Michele Bachmann, whose campaign has shown signs of falling apart over the last week, scraped together enough cash for a television ad in which she repeatedly compares herself to Margaret Thatcher. On the campaign trail, she is billing herself as having the potential to become 'America's Iron Lady'.
Her meagre ad spending contrasts with other candidates, who between them have racked up $13m in spending, about a third of it by Romney or his supporters.
The Democratic party leadership has decided that, in spite of lack of enthusiasm displayed by many conservatives towards him, Romney is eventually going to win the Republican nomination to take on Barack Obama for the White House in November.
The Democrats, as well as unions supporting the party, have sent representatives to Iowa to take advantage of the large media presence to mount attacks on Romney. Among those in Iowa to embarrass Romney was a vocal victim of lay-offs during Romney's time as chief executive of Bain, a private equity firm.
Jobs are an emotive issue at a time when the unemployment rate in America is running at 8.6%. The Democratic line of attack also plays into voter hostility towards big business.
Romney was holding four rallies throughout Iowa on Monday, ending with a late-night one on the outskirts of Des Moines at a goods manufacturer called Competitve Edge. That may or may not turn out to be prophetic.
Romney's team appear confident they will take first place on Tuesday night, providing a strong base for the contests to come later in January: New Hampshire, South Carolina and Florida. They would ideally like to have the nomination resolved by then in order to concentrate on Obama.
Conscious that a late surge by Santorum could upset his plans, Romney for the first time criticised Santorum on Sunday, saying he "has spent his career in the government in Washington". Romney is attempting to capitalise on the widespread anti-Washington mood.
Perry, who has paid for a stream of ads critical of Santorum over the last few days, returned to the attack again on Monday, recalling Santorum's humiliating double-digit defeat in 2006 when he failed to recapture his Pennsylvania Senate seat.
Perry, homing in on one of Santorum's biggest weak spots, said that Santorum had demonstrated he could not win races against liberal Democrats when it mattered.
Paul, quirky as ever, was the one candidate who took a two-day holiday for New Year, returning to his home in Texas. He was out on the campaign trail yesterday with his son Rand, a Republican senator from Kentucky.
The candidates are already looking beyond Iowa to New Hampshire, whose primary is to be held on 10 January. Paul began running an ad in New Hampshire highlighting local Republican politicians who are endorsing him and voicing criticism over the growth of federal government, a popular theme in a state.
Romney is favourite to win New Hampshire, where he has a 19% lead in polls.