Former Pennsylvania senator Rick Santorum on Wednesday thanked Iowans for propelling him forward even when he was running in the low single digits in opinion polls prior to Tuesday's caucuses.

Santorum was in a dead heat early Wednesday with former Massachusetts governor Mitt Romney in the Iowa caucus, the first contest of the Republican Party's presidential nominating race. Both stood at 25 per cent of the vote with 99 per cent of the results in.

He acknowledged that political analysts see Romney as more likely to win against President Barack Obama in November general elections.

"What wins in America are bold ideas, sharp contrasts and a plan that includes everyone," Santorum said, outlining his policies. "A plan that includes people from all across the economic spectrum, a plan that says we will get America to work."

Meanwhile. former Massachusetts governor Mitt Romney celebrated his dead-heat finish Tuesday night atop the Iowa caucuses, the opening contest of the Republican Party's presidential nominating race.

Romney had spent little time and money in Iowa until the last several weeks, having put greater campaign effort last year into the January 10 New Hampshire primary.

"We don't know what the final vote tally's going to be," Romney said, as the top candidates remained just a few votes apart.

"This is a campaign night where America wins," said Romney, flanked by his wife and sons. "We're going to win the White House and get America back on track."