KARL (voice-over): We asked Rick Perry about that. He says he has no regrets for the negative ads he's run against Gingrich.
PERRY: We've just been telling the truth about their records. It's not like they played powder-puff with me.
KARL: With Newt's collapse, look who's rising. Until this week, Rick Santorum barely registered in the polls and couldn't seem to buy a crowd. Now Santorum may be the hottest candidate in Iowa.
SANTORUM: How are you?
KARL (on-screen): I mean, you (OFF-MIKE) handful of people, and all of a sudden you've got...
SANTORUM: It doesn't really -- to be honest with us, it doesn't feel really that much different. It really doesn't. I mean, I'm still doing what I'm doing.
KARL (voice-over): Michele Bachmann had an even worse week than Gingrich. Way down at the bottom of the polls, she ends up going on the attack against her own Iowa co-chairman who jumped ship to support Ron Paul.
BACHMANN: He told me that he was offered money, he was offered a lot of money by the Ron Paul campaign.
KARL: And it was the week that ended in tears for Newt Gingrich, when at a town hall meeting of Iowa moms, he was asked by Republican pollster Frank Luntz about his mom, who suffered from depression.
GINGRICH: You know, I mean, but dealing with, you know, the real problems of real people in my family...
KARL: And that brings us to trending. Romney, up. The conservative anti-Romney vote is divided, and he's smelling victory. Newt Gingrich, down, but he's been there before. Up, Rick Santorum. Nobody's rising faster in Iowa. Rick Perry, up. He's picking up Gingrich defectors and still spending lots of cash. Up, Kelly Clarkson. She endorses Ron Paul and watches her CD sales go up 200 percent. Down, the Ames straw poll. Remember when Bachmann won? Now she's hoping to avoid a last-place finish.
For this New Year's edition of "This Week in Politics," I'm Jonathan Karl. Jake?
TAPPER: Thank you to Jon Karl.
TAPPER: Now let's turn to Congressman Ron Paul. Many political observers say he's on track to win in Iowa, but today he's back home in Texas. Congressman Paul, welcome, and happy new year.
PAUL: Thank you. Nice to be with you.
TAPPER: So your rivals have really started to unload on you in the home stretch, given your prominent perch in the polls. Newt Gingrich says your views are, quote, "totally out of the mainstream of every decent American." Jon Huntsman has a web ad calling you unelectable, citing a decade worth of newsletters published under your name containing bigoted statements against minorities. And even the Des Moines Register poll that shows you essentially tied for first with Mitt Romney says that you are leading the pack in terms of who is least electable in a general election.
This is a real area of vulnerability for you. How do you convince Republican voters that you are, in fact, electable against President Obama?
PAUL: Well, that whole thing is a contradiction in terms. If I'm leading in the polls, that means I'm electable. I've been elected 12 times in Texas, when people get to know me. We're doing well in the polls. Our crowds are getting bigger. And the people who are complaining are the ones who are way down in the polls, so they don't have a whole lot of credibility about my electability.