DES MOINES, Iowa (AP) -- With time running short, Ron Paul, Rick Santorum and other Republican presidential contenders argued Sunday that they could beat President Barack Obama as they worked to persuade undecided Iowa Republicans aching to win the White House to choose them over chief rival Mitt Romney.
"I'm the candidate that actually was able to win in states, as a conservative, in getting Democrats and independents to vote for us," Santorum, the former Pennsylvania senator who is surging in the race and is a favorite among cultural conservatives, said in an interview on CNN. "Mitt Romney has no track history of doing that."
Paul, a libertarian-leaning Texas congressman who Romney has said is outside the GOP mainstream, countered the suggestion that he's a fringe candidate. In an interview with ABC from his home state, where he was spending the weekend, Paul insisted: "I'm electable. I've been elected 12 times in Texas, when people get to know me."
With Romney in a position of strength in Iowa, both Santorum and Paul went directly at the former Massachusetts governor's chief argument -- that he is the most electable Republican in a head-to-head matchup against Obama next fall. They hope they can sway the roughly half of likely caucus-goers who say they are undecided or willing to change their minds two days before the leadoff presidential caucuses.
A Des Moines Register poll released Saturday showed Romney and Paul locked in a close race, with Santorum rising swiftly to challenge them. Nearly half of likely Iowa caucus-goers view Romney as the Republican most likely to win the general election. He was far ahead of Santorum and Paul, who was viewed as the least likely to win.
Those two are fighting against the notion in GOP circles that their bases of support are narrow and neither would be able to cobble together the diverse voting coalition necessary to beat Obama in November. Paul attracts legions of backers who put states' rights above much else, while Santorum -- an anti-abortion crusader -- is popular among Christian conservatives who make up the base of the Republican Party.
In contrast, Romney has styled himself during this campaign as a Republican able to attract a broad spectrum of voters. As polls showed him in strong standing in Iowa in the past week, he has redoubled his effort to portray himself as the business-savvy executive with national appeal who is best able to defeat Obama on the campaign's most pressing issue, the economy.
Although the race remains fluid, it appeared that Romney's carefully crafted plan to avoid underperforming in Iowa, where he campaigned little until last week, may be working, given a divided GOP electorate torn between several more conservative candidates and Paul's appeal to libertarians.
The issue of what type of candidate to choose cuts to the heart of why the Iowa race is so volatile; an NBC/Marist poll last week showed nearly even percentages of Iowa caucus-goers want a candidate who shares their values as want a candidate who can beat Obama.
"The first thing you see when you talk to any Iowa Republican is that desire to beat Barack Obama," Iowa GOP Chairman Matt Strawn said on CNN.
Mindful of that, both Romney and Santorum canvassed the state Sunday as they cast themselves as the strongest contender -- and their schedules illuminated their late-game strategies for rallying their backers to the polls.
Romney was set to appear in Atlantic and Council Bluffs as he works to maximize the edge he holds in critical areas, especially those he won in his second-place finish here four years ago, rather than risk underperforming in places where more ardent conservatives are leery of his Mormon faith and shifting positions on social issues. On Monday, he was heading to his eastern Iowa strongholds, Cedar Rapids, Davenport and Dubuque.
During campaign stops in Iowa over the weekend, Romney repeatedly projected confidence that he would be the GOP's nominee this year, promising to return to Iowa, a general-election swing state, in the fall campaign.
Santorum, for his part, was campaigning deep into GOP-rich rural northwest Iowa Sunday, with stops in conservative counties won by Mike Huckabee during the former Arkansas governor's victorious campaign here four years ago.
As he met voters, his final ad for Iowa TV called him "a full spectrum conservative" who is most likely to beat Obama and the "trusted conservative who gives us the best chance to take back America."
The activity of their rivals was more muted.
Paul, who has slipped somewhat in the wake of attacks on his foreign policy positions, remained out of the state for a second straight day. But he did a few national TV interviews from Texas, where he celebrated the New Year with his family.
In the interviews, he argued that the majority of Americans are with him when it comes to a non-interventionist foreign policy.
"I would say that I'm pretty mainstream," he told CNN. "I think that people who are attacking me now are the ones who can't defend their records, and they've been all over the place."
Along with Romney, Texas Gov. Rick Perry, former House Speaker Newt Gingrich and Minnesota Rep. Michele Bachmann -- all of whom are trailing in polls and fighting for the support of Christian evangelicals -- spent the morning in church.
"Romney would buy the election if he could," Gingrich, who has fallen steadily in the polls since early December, told reporters after attending mass in Des Moines with his wife, Callista.
Gingrich later waded through a busy sports bar packed shoulder-to-shoulder with more than 200 people and a heavy contingent of press without stopping to speak to the crowd.
Bachmann and Perry tried to make the electability argument while assailing Santorum, who suddenly has found himself the target of sharp attacks on his conservative credentials from rivals vying for the same bloc of voters.
Bachmann told ABC, "I have the best ability to take it to Barack Obama in the debate and hold him accountable." On Fox, she lambasted Santorum, noting that he was soundly defeated when he ran for re-election in 2006, losing by a 59-41 margin to Democrat Bob Casey.
"I won four races in the last four years, in the toughest years for Republicans -- in a liberal state like Minnesota, I won," Bachmann said.
Perry, who never lost an election in Texas but has struggled in his first nationwide race, told "Fox News Sunday" of his opponents, "They may do OK in Iowa, but when it comes to running a national campaign, they're going to falter."
Looking for a late-game lift, Perry also renewed his attack on Santorum, saying: "He's got a spending problem. He's got an earmark problem. He voted eight times to raise the debt ceiling in the United States Senate."