Republican Mitt Romney narrowly leads rival Ron Paul in Iowa three days before the state kicks off the party's 2012 presidential nominating race, according to a Des Moines Register poll released on Saturday.
The closely watched poll, which has a strong track record in Iowa races, showed Rick Santorum surging past Newt Gingrich into third place in a fluid battle where 41 per cent of likely caucus-goers said they could still change their minds.
The newspaper poll, conducted Tuesday through Friday, showed Romney with 24 per cent support and Paul with 22 per cent, within the margin of error of 4 per cent and similar to other polls showing the two battling for the top spot in Iowa.
Santorum had 15 per cent support and Gingrich 12 per cent. In fifth place was Rick Perry with 11 per cent, and Michele Bachmann was sixth with 7 per cent.
The poll was released as candidates launched the final stretch for Tuesday's contest in Iowa, the first in the state-by-state battle to choose a Republican challenger to President Barack Obama, a Democrat, in the November election.
The results were a boost to Romney, who has resumed his front-runner's role in the Republican presidential race in the last few weeks after the slide of Gingrich.
A victory for Romney in Iowa, combined with a win in the next contest on January 10 in New Hampshire, could put the former Massachusetts governor on a path to clinching the Republican nomination early.
But Santorum was the candidate with momentum in the closing days of the race. The Register poll was taken over a four-day period and the newspaper said that in the final two days of polling, Santorum was in second place with 21 per cent.
Romney stayed the same at 24 per cent.
The poll was more bad news for Gingrich, the former House speaker who led the race a few weeks ago but has faded under an onslaught of attack ads from Paul and an outside group that backs Romney.
At a stop in Iowa earlier on Saturday, Gingrich said he would adjust his campaign strategy to respond more forcefully to the attacks.
In Iowa's quirky caucus system, voters gather to cast ballots in public meetings after listening to pitches on behalf of the candidates.
Romney returned to Iowa after a morning appearance in New Hampshire and refrained from mentioning any of his Republican rivals, targeting his attacks on Obama's handling of the struggling US economy and foreign policy.
"I see this election as not just an election to replace a president. I see this as an election to save the soul of America," he told a crowd that jammed a restaurant in Le Mars in conservative western Iowa.
Paul, a libertarian congressman who has a loyal and active group of supporters and a strong campaign organization in Iowa, is taking the holiday weekend off in Texas before returning to Iowa on Monday.
Santorum, a former US senator from Pennsylvania with a strong social conservative message, was trying to unite Iowa's influential evangelical Christian voters behind him and score an upset with a surge in the final days.
"If you really want to transform America, it has to be about values, faith and freedom," he told a crowd in Knoxville, Iowa.
Santorum said Romney victories in Iowa and New Hampshire would not end the race.
Conservative South Carolina, which votes on January 21, will be next up on the schedule, and a conservative who can rally anti-Romney voters will be a powerful force.
Many social conservatives distrust Romney because at one time he backed abortion rights and signed a Massachusetts healthcare law similar to Obama's federal plan.