Republican presidential hopeful, Rick Santorum (R) signs a man's hat at a local restaurant as he arrives to campaign and watch a football game in Ames, Iowa

AFP

Mitt Romney urged Iowa voters to give him what could be a decisive "boost" over his rivals for the Republican presidential nomination in the heartland state's caucus, just two days away, reports AFP.

Romney -- who portrays himself as the strongest candidate to beat President Barack Obama in November elections -- has retaken a thin lead in Iowa before the state casts the first ballots of the Republican nominating process on Tuesday.

"I can't tell you who's going to win this thing," the former Massachusetts governor and millionaire venture capitalist said after chatting and shaking hands with scores of people in a packed diner.

"But I do believe that I'm going to have a great deal of support and that that will give me the kind of boost I need as I go into a season of (contests in) a number of other states," he said. "This is a process that begins here."

Romney has made little secret that he hopes a strong showing here -- coupled with a victory in New Hampshire a week later -- could help him lock up the nomination early in the state-by-state process of picking a standard-bearer.

But with four in 10 Iowans telling pollsters they could still change their minds, veteran Texas Representative Ron Paul stood within striking distance of Romney.

"I may come in first, I may come in second. I doubt I'll come in third or fourth," Paul, known for anti-interventionist and libertarian views that have drawn heavy fire from his rivals for the party's nomination, told CNN.

And firebrand social conservative Rick Santorum's support was surging as Iowa's evangelical Christians, a critical Republican bloc, seemed to be rallying behind the former senator from the battleground state of Pennsylvania.

"Our support is rising here. But there's two more days and there's a lot of work to be done," he said at a rally in Sioux City.

The Des Moines Register newspaper's final poll before the caucus found Romney with 24 percent support, Paul at 22 percent, Santorum at 15 but rising, and 41 percent of likely voters saying they could still change their minds.

The survey found 12 percent support for former House speaker Newt Gingrich, 11 percent for Texas Governor Rick Perry, and seven percent for Minnesota Representative Michele Bachmann.

"Tuesday night people are going to see a miracle," said Bachmann, whose long-shot hopes rest heavily on Iowa. "People make their decision, quite honestly, in the caucus room."

"We are going to do good on Tuesday," Perry said on Fox News Channel, deriding his rivals as "either Washington insiders or Wall Street insiders."

And Gingrich -- whose support has plummeted in the face of a barrage of attack ads, many by a group backing Romney -- took aim at the frontrunner, charging "he would buy an election if he could."

Romney scoffed, saying here the election "is not being driven by money raised, it's being driven by message, connection with the voters, debates, experience."

After Iran defiantly declared it had tested a new medium-range missile and made a significant advance in its nuclear program, Santorum told NBC television he would pummel Tehran's nuclear sites with air strikes unless they are opened wide to international inspectors.