AMANPOUR (voice-over): This week -- the fighting front-runner. Newt Gingrich, target of the night at the ABC News debate in Iowa. Taking hits.
FORMER GOV. MITT ROMNEY (R-MA.,), PRESIDENTIAL CANDIDATE: We need people from outside Washington, outside K Street.
AMANPOUR: And returning fire.
FORMER REP. NEWT GINGRICH (R-GA.), PRESIDENTIAL CANDIDATE: The only reason you didn't become a career politician is you lost to Teddy Kennedy in 1994.
AMANPOUR: Under pressure, Mitt Romney wages big.
ROMNEY: I tell you what, 10,000 bucks, a $10,000 bet?
AMANPOUR: But will his gamble backfire? And did Michele Bachmann outflank the front-runners with her conservative attack?
REP. MICHELE BACHMANN (R-MINN.), PRESIDENTIAL CANDIDATE: Newt Romney, they were for Obamacare principals. Newt Romney. Newt Romney.
AMANPOUR: Also, Rick Perry gets personal.
GOV. RICK PERRY (R-TEXAS), PRESIDENTIAL CANDIDATE: If you cheat on your wife, you'll cheat on your business partners.
AMANPOUR: The ABC News debate, a turning minute in this roller-coaster campaign.
This morning, complete coverage. Analysis from the moderators, Diane Sawyer and George Stephanopoulos. Reaction from Jon Huntsman, the other Republican in the race. Our ABC News political team is standing by in Iowa to break down the spin. And our roundtable is on hand with the long view of this unpredictable race.
AMANPOUR: Good morning, and welcome to the program. We'll have all the highlights of last night's showdown in the Hawkeye State. But some news since your morning papers. Iran has announced that it won't return the American surveillance drone now in the hands of the country's military. A top commander of the Revolutionary Guard called the drone's incursion into Iranian air space a hostile act and warned of a bigger response if it happens again. The spy plane was put on display earlier this week, and it's considered a trove of sensitive information.
In Russia this morning, another day of unprecedented protests against Prime Minister Vladimir Putin, who wants to become president again. Tens of thousands took to the streets yesterday, and today crowds numbered in the hundreds. These are the largest demonstrations in the post-Soviet era, as Russians rally against voter fraud and call for Putin to step down.
And here in the United States, all eyes are on Iowa, where six Republican presidential candidates did battle in the ABC News debate last night. The showdown was the clear highlight of this week in politics. And of course, our man Jon Karl was there to take us through the highs and the lows.
JON KARL, ABC NEWS: Newt Gingrich said he would stay positive. But when Mitt Romney suggested he was a career politician, Gingrich couldn't resist.
GINGRICH: Let's be candid. The only reason you didn't become a career politician is you lost to Teddy Kennedy in 1994.
ROMNEY: Now, wait a second. Now, wait a second.
KARL: Gingrich took fire from everyone on the stage. Bachmann said he was no different than Mitt Romney on the big issues.
BACHMANN: If you look at Newt Romney, they were for the $700 billion bailout. You just heard, Newt Romney is also with Obama on the issue of the payroll extension.
ROMNEY: He and I are not clones. I promise. That is not the case.
KARL: The oddest moment of the debate?
PERRY: You were for individual mandates, my friend.
ROMNEY: You raised that before, Rick.