Republican presidential candidates prepared Tuesday for their first major test of the primary season, making last-minute whistle-stops throughout Iowa in hopes of swaying many undecided caucus-goers.
Later tonight, Iowa Republicans will gather to cast ballots for the person they want to stand against President Obama in November. But after a bruising months-long campaign, more than a third of those participating in the caucuses say they still haven't made up their minds.
A Des Moines Register poll released Saturday found 41 percent of likely caucus-goers could be persuaded to change their minds, while another 7 percent had no first-choice candidate; 1 percent said they were not sure who to support.
A Three-Man Race
Polls show the race in Iowa has narrowed to a three-man contest among former Massachusetts Gov. Mitt Romney, Texas Rep. Ron Paul and former Pennsylvania Sen. Rick Santorum.
Republican voters will gather at 8 p.m. ET in the living rooms of private homes, school auditoriums and libraries, where they will write the name of their favorite on blank pieces of paper. While only a small percentage of Iowans will attend the caucuses, the state vote holds outsize importance in the nominating process because it is the first test of the candidates' popularity and ability to organize.
Romney was set to hold a rally Tuesday in the capital, Des Moines, while Santorum planned to join a couple of other candidates at a Rock the Vote event for local high school students. Texas Gov. Rick Perry was preparing a final push, meeting early Tuesday with his volunteers and then holding two town hall-style meetings.
"We're going to win this thing," Romney told a rally Monday on the last full day of campaigning.
But by Tuesday morning, Romney was backpedaling, telling MSNBC television: "It's hard to predict exactly what's going to happen. I think I'll be among the top group."
Paul, a small-government libertarian, has found fertile ground in Iowa for his states' rights, anti-war message. In the Des Moines Register poll, Paul trailed Romney by just 2 percentage points.
At a downtown Des Moines hotel on Monday, Paul opined on the limited role of government.
"What is the proper role? Stay out of running the economy. Stay out of our personal lives, and stay out of the personal affairs of other nations," he said.
Santorum has gained ground among conservative Christians, who like his anti-abortion record and see Romney as too centrist.
"Do not settle for less than what America needs to transform this country. Moderate candidates who try to appeal to moderates end up losing," Santorum said Monday in a slap at Romney, who is seen by some as a flip-flopper who implemented a statewide health system in Massachusetts that later became a model for President Obama's health care overhaul.
Priority No. 1
But Romney may withstand those challenges because many Iowa Republicans see him as the candidate most likely to defeat Obama.
At a Monday night rally in Davenport, voter Nancy Rudnick told NPR that she thought Romney "has the ability to turn this country around and to beat Obama." Asked which of the two was most important, she answered: "Beating Obama."
Former House Speaker Newt Gingrich, who briefly looked like a front-runner, has seen his Iowa poll numbers plummet in the past few weeks as a series of negative ads sponsored by a pro-Romney political action committee began to take a toll.
On Monday, Gingrich even went so far as to predict his own defeat in tonight's caucuses.
Standing in front of what is said to be the world's largest tractor in the city of Independence, he nevertheless insisted that his intellect and his experience should be enough for him to win the White House.
"I am the only candidate who could successfully debate Obama in the fall, and I'm the only candidate who has an actual track record twice, with [President Ronald] Reagan and then as speaker, of actually changing Washington," Gingrich said.
Minnesota Rep. Michele Bachmann also once led in Iowa. But at an appearance in front of her bus in West Des Moines, she too almost sounded as though she were conceding: "To be able to campaign for the presidency of the United States, to be able to be the first woman in the history of the Iowa Straw Poll to win that straw poll, it's been a thrill for me to do this."
Romney had largely stayed away from Iowa, thinking his chances weren't good, but made an 11th-hour push once it became clear that he had a chance of winning, campaign adviser Eric Fehrnstrom told NPR.
"I think we're surprised to find ourselves in the hunt here in Iowa," he said. "Back in the spring we didn't think that we'd do that well in Iowa, but based on what we've been seeing and hearing over the past several weeks, we decided to invest more time by the candidate here."
Looking Beyond Iowa
Fehrnstrom downplayed the importance of a single test that comes so early in the primary season, saying that the focus should remain on defeating Obama.
Iowa will send just a few dozen delegates out of the nearly 1,150 that will be needed by any candidate to wrap up the GOP nomination at the party's national convention this August in Tampa, Fla.
"There's a sense that even if Ron Paul or Rick Santorum takes first place in Iowa ... in the long term that's not necessarily a terrible thing for the Romney campaign," he said.
"I think whether we win or achieve something less in Iowa, we've built an organization that can go the long distance to Tampa," Fehrnstrom said.
After Tuesday's vote, Romney, Gingrich and Santorum planned to leave for New Hampshire. Romney holds a commanding lead in polls there and will be in a strong position to win the state's Jan. 10 primary even if he doesn't pull out a victory in Iowa. Paul plans to join his rivals in New Hampshire later in the week.
Perry and Bachmann don't plan to compete in New Hampshire, instead heading straight from Iowa to the first-in-the-South primary, set for Jan. 21 in South Carolina. Romney also plans to visit South Carolina this week.
NPR's Ari Shapiro, Don Gonyea and Ted Robbins reported from Iowa for this story, which contains material from The Associated Press.