(CNSNews.com) – Hours before the caucuses convene in Iowa, Former House Speaker Newt Gingrich called his fellow Republican Mitt Romney a liar on national television Tuesday morning.

"Well, you seem shocked by it," Gingrich told CBS correspondent Nora O'Donnell, who was anchoring CBS' "The Early Show" Tuesday morning.

O'Donnell had just asked Gingrich, "Are you calling Mitt Romney a liar?

"Yes," replied Gingrich, who has complained about attack ads produced by independent political action committees that have endorsed Romney.

"Why are you saying he's a liar?" O'Donnell asked.

"Because this is a man whose staff created the PAC, his millionaire friends fund the PAC, he pretends he has nothing to do with the PAC --it's baloney. He's not telling the American people the truth.

"It's just like this pretense that he's a conservative. Here's a Massachusetts moderate who has tax-paid abortions in 'Romneycare,' puts Planned Parenthood in 'Romneycare,' raises hundreds of millions of dollars of taxes on businesses, appoints liberal judges to appease Democrats, and wants the rest of us to believe somehow he's magically a conservative.

"I just think he ought to be honest with the American people and try to win as the real Mitt Romney, not try to invent a poll-driven, consultant-guided version that goes around with talking points, and I think he ought to be candid. I don't think he's being candid and that will be a major issue. From here on out from the rest of this campaign, the country has to decide: Do you really want a Massachusetts moderate who won't level with you to run against Barack Obama who, frankly, will just tear him apart? He will not survive against the Obama machine."

Romney, asked for his response a short time later on Fox & Friends, brushed off Gingrich's comments:

"Well, I understand Newt must be very angry, and I don't exactly understand why -- but look, I wish him well. It's a long road ahead and he's a good guy. I like he and Callista, and we've got many months ahead of us, so I'll leave it at that."

Romney said he has no control over ads run by an independent PACs that have endorsed him. He also noted that Gingrich is having "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 said he will continue to defend his record. "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?"