Republican Ron Paul, a leading contender in Iowa's presidential caucuses, said Monday on the eve of the leadoff 2012 vote that he does not envision himself in the White House.

The Texas congressman, near the top of the polls in Iowa, said the odds of him winning are slim and admitted that the path to the nomination was unclear without a strong performance in Iowa and the New Hampshire primary next week.

When asked Monday during an ABC News interview in Des Moines whether he sees himself in the Oval Office, Paul replied: "Not really, but I think it's a possibility."

He added: "I don't deceive myself. You know what the odds are. The odds have been slim."

Paul made the comments after a five-city blitz where he headlined large, enthusiastic crowds packed with younger voters, re-emerging in the state after spending two days out of Iowa at home in Texas while his rivals blanketed the state.

Campaigning with a son, Sen. Rand Paul, R-Ky., the libertarian-leaning Texan defended the 48-hour break, even as final polls published at the end of last week showed more than a third of likely caucus-goers undecided or willing to change their mind before the caucuses.

Paul expressed faith in his Iowa organization, a far more structured network than his 2008 Iowa campaign that helped him place fifth in Iowa four years ago.

"I don't want to sound over-confident, but I am confident in our organization," he said, arguing that other candidates were still scrambling to shore up their supporters. Paul has a robust staff in New Hampshire, and he began running ads in South Carolina, where the South's first primary is scheduled for Jan. 21.

Still, Paul was waiting until Friday to head to New Hampshire, where he is rising but far behind former Massachusetts Gov. Mitt Romney in polls.

Paul's confidence was buoyed Monday by big crowds in Des Moines, Davenport, Cedar Rapids, Cedar Falls and Mason City. Paul completed the circuit in a small chartered jet.

"We're optimistic and have our fingers crossed you're going to show up and do your job," Paul told about 200 people in Mason City, the final stop of the day.

Paul has a robust campaign organization in New Hampshire, which holds its primary Jan. 10, and begun airing ads in South Carolina, scheduled to vote on Jan. 21.

But he said he does not know how he will compete deeper into the nominating campaign.

"It will be a real challenge. There's no doubt," Paul told The Associated Press aboard the plane between Davenport and Cedar Rapids. "We've invested a lot of time and money in doing well here."

Still, Paul stoked the crowds along the way, railing equally against Democrats in Congress as he did against Republicans. At each stop, he criticized the Patriot Act as an abuse of civil liberties despite its support from his own party's leadership.

Paul has steadily gained ground in Iowa in the last two months. And while he narrowly trailed only Romney a series of polls published last week, support had leveled off in the wake of sharp attack over his opposition to preventing an Iranian nuclear weapon with a military strike.

It did not dissuade him from repeating in Davenport and Cedar Rapids a line that brought loud cheers in Des Moines. "Just listen to some of the candidates. They are willing to start bombing Iran right now. One thing is for certain, this country does not need another war," Paul told the crowd in Davenport, prompting loud cheers.

And while Paul himself steered clear of criticizing his rivals, his son Rand repeatedly struck at Santorum, who has supported foreign aid spending, a rallying point of opposition for fiscal hawks including tea party supporters.

"You've got so-called GOP candidates for president traipsing round Iowa who have voted for foreign aid," Rand Paul said to a cheering crowd of more than 300 in Cedar Rapids.

The campaign was preparing an automated call criticizing Santorum's support for foreign aid and other parts of the former senator's fiscal record.

Still, Paul said he was as much rallying a movement to change politics in America as he was campaigning for president.

"I don't know why you have to separate the two," he told ABC News.