Republican debate: Gingrich likens himself to Ronald Reagan

Republican front-runner Newt Gingrich likened himself to Ronald Reagan and insisted in a campaign debate Thursday night that he can defeat President Barack Obama in 2012, adding it was laughable for his rivals to challenge his conservative credentials.

Gingrich and former Massachusetts Gov. Mitt Romney — who runs second to Gingrich in the polls in Iowa — joined five other White House hopefuls on a debate stage for the last time before Iowa's Jan. 3 caucuses lead off the battle for the Republican presidential nomination.

The big question in the opening moments of a fast-paced two-hour debate went to the heart of a dilemma that could eventually settle the race — do conservative Republican voters pick a candidate who best represents their party's views, or do they simply want the candidate who is best able to defeat the president?

Those voters begin making that choice on Jan. 3, and if experience is any guide, one or more of the presidential hopefuls on the debate stage will not make it out of the state to compete in the New Hampshire primary a week later.

Romney said his experience in private business made him the man to confront Obama in debates in 2012. "And I'll have credibility on the economy when he doesn't," he said.

The Republican primary winner faces Obama, whose favorable ratings have declined sharply, mostly because of his inability to unleash a strong economic recovery. Unemployment remains at a high 8.6 percent.

Gingrich, who seemed an also-ran in the earliest stages of the race, has emerged as a leader heading into the final stretch of the pre-primary campaign. He now leads the Republicans in the polls both in Iowa and nationally.

However, his conservative credentials were immediately challenged: Former Sen. Rick Santorum recalled that as House of Representatives speaker Gingrich had to contend with a "conservative revolution" from the ranks of Republican lawmakers.

Indeed, Gingrich is encumbered with a history of having left the House under a cloud of ethics complaints, and he has had three marriages and admitted marital infidelities.

Romney largely refrained from criticism of Gingrich, despite increasingly barbed attacks in day-to-day campaigning, including a characterization of the former speaker as "zany" for having endorsed mining the moon and lighting highways with mirrors in space.

Romney, who has been attacked for shifting positions on several issues held dear by conservatives, firmly rejected suggestions he once favored same-sex marriage only to change his position. "I have been a champion of protecting traditional marriage," he said.

Gingrich had set the stage for the debate by pushing back against criticism from Romney and pledged in a new ad to be positive in the race.

In a forceful attack, Minnesota Rep. Michele Bachmann said Gingrich "had his hand out and received $1.6 million to influence senior Republicans and keep the scam going in Washington, D.C.," for Freddie Mac, a government-backed housing entity.

"Just not true," Gingrich shot back. "I never lobbied under any circumstances," he added, denying an allegation she had not made.

The rivals also discussed illegal immigration, with Romney saying he's all for immigration, as long as it's legal and policies don't reward those who are already here. He said workers who have come to the U.S. illegally would have to leave the country but would be eligible to apply to return as long as they went to the back of the line.

Gingrich said Americans have to be realistic in confronting the millions of workers without documentation. But he also said he would cut off funding for so-called sanctuary cities that harbor illegal immigrants and would drop federal lawsuits against states with tough anti-immigration laws.

The wild card in the Iowa race is Texas Rep. Ron Paul is, with the small-government libertarian surpassing Romney in some polls of the state's voters. Paul said the U.S. has no legitimate claim to block Tehran from developing a nuclear weapon, while Bachmann called his position wildly dangerous.

Also participating in the debate were Texas Gov. Rick Perry and former Utah Gov. Jon Huntsman. Huntsman is not campaigning for the Iowa caucuses but has recently gained on Romney in next-up New Hampshire.