As the clock ticks down to the first votes in the Republican presidential race, Newt Gingrich is declining to reject a depiction of rival Mitt Romney as a “liar” and decrying Romney's record as Massachusetts governor as anything but conservative.

Romney responded quickly, dismissing Gingrich as "very angry."

The brouhaha began after a reporter asked Gingrich to clarify comments he made on the campaign trail. Asked whether he was calling Romney "a liar" over the frontrunner’s record, Gingrich responded: "Yes. I mean, what else could you say?"

"Romney fails to tell the truth on three levels," Gingrich later told Fox News.  "He won't tell the truth about his own record; he is at Massachusetts moderate, not a conservative; he has failed to -- refused to -- tell the truth about his super PAC, which is run by his staff and funded by his millionaire friends.  And his super PAC runs ads that are just plain lies."

"Well, I understand Newt must be very angry, and I don't exactly understand why," Romney responded on Fox News after Gingrich’s initial charge.  "I know that it's always tempting to look for someone else to blame, but at some point, you've got to stop and say, OK, what things can I do better?

“I'm going to keep battling my campaign in the way I think is best and defending my record,” Romney continued. “If the speaker decides to come after me, why, that's part of the process.  I'm ready for it, and my shoulders are wide. If I can't handle this kind of attack, why, how in the world would I handle the attack that's going to come from President Obama?"

Gingrich has repeatedly called out the other GOP presidential candidates -- Romney, in particular -- for airing negative ads in Iowa, many of which have targeted the former House speaker as less than conservative himself. Gingrich said aside from being wrong, Romney is also plain feckless when he claims he has no authority to stop the ads, which are not coordinated by the campaign.

"I've asked Romney for three weeks to tell his PAC to quit running negative ads. I've pointed out again and again that this is a terrible way to run for office," Gingrich said. "We have stayed positive.  All of my ads remain positive."

Gingrich also suggested that Romney is unwise to compare the ads as mild compared to what President Obama’s reelection camp will do.

"I wouldn't personally use that kind of comparison, and say that my campaign's kind of like Obama, but smaller, but he did."

Romney, however, said that the problem lies with Gingrich's poll numbers, not political advertising.

"The super PAC that happens to endorse me has put some ads out -- I can't control those.  We're not allowed to have a coordination between a campaign and these independent PACs," Romney said.  "I'm sure they may have had an effect, but you know, the speaker's had just as much difficulty in the polls in New Hampshire as he has in Iowa, and I don't think there are any negative ads going on there." 

Romney went on to defend his "conservative record," citing policies he said he implemented as governor of Massachusetts, including lowering taxes, cracking down on illegal immigration and reforming education.

"I'm proud of my conservative record," he said.  "I think it will stand up to virtually anyone else in this race."

But Gingrich refused to back down from his assertions, saying that he simply answered a direct question in an honest manner.

"I'm not going to lie on an interview," he said.  "I think what's sick about Washington is all these people who smile and are phony and pretend, and in fact they are crippling the country by their unwillingness to tell the truth and to be honest."

While the outcome of the Iowa caucus remains a mystery, Gingrich has seen his recent, meteoric surge in the polls wane in recent days.  He acknowledged that he's unlikely to finish in a high place in Tuesday's caucus, and said that he would support Romney if he becomes the party's eventual nominee.

"I think it'll be a very hard campaign," Gingrich said.  "If he's the nominee, I'll support him.  But I think it's very challenging, because Obama's going to have a billion dollars and he will do anything to win reelection."