It was the final meeting of the final four GOP candidates before Saturday's South Carolina primary, and with Rick Perry out of the race, the poll numbers are tightening between Mitt Romney and Gingrich.
But Gingrich isn't helped any by an interview his second wife did with ABC News. Marianne Gingrich spoke publicly for the first time, saying Gingrich wanted an open marriage, but she refused.
"I said to him, 'We've been married a long time,' and he said, 'Yes, but you want me all to yourself. Callista doesn't care what I do,'" she said.
She said Gingrich conducted an affair with Callista Bistek - his current wife - "in my bedroom in our apartment in Washington" while she was elsewhere.
John King, the moderator of the GOP debate, wasted no time addressing the allegations. Newt Gingrich fired back with a scathing attack on the media.
"I think the destructive, vicious, negative nature of much of the news media makes it harder to govern this country, harder to attract decent people to run for public office, and I am appalled that you would begin a presidential debate on a topic like that," he said.
His response got him a standing ovation, but the ABC News interview could complicate matters for Gingrich two days before the South Carolina primary. It's a state where he polls lower among conservative women.
Gingrich's two daughters from his first marriage are coming to their father's defense.
"What people need to remember is this happened a long time ago. And we wish Marianne no ill will, we wish her the best, but it happened a long time ago," said Gingrich's daughter, Jackie Cushman.
Some residents in Columbia say the interview may make a difference to the conservative voters in a state where the majority are evangelicals. Resident Fritz Hamer, a Democrat, said he isn't sure the Gingrich interview will have much of an impact.
"On the surface, you'd think it'd play real bad, but for some reason, the right-wing Republicans can rationalize out of things if they think it will help their party," he said.
Meantime, Gingrich got a boost Thursday from a former opponent. Texas Gov. Rick Perry announced he was quitting the race and endorsing Gingrich.
Perry said at a news conference that he concluded there was no "viable path forward" for him in the race. He called Gingrich a "conservative visionary."
Perry entered the race last August with high numbers in polls, but his standing fell after a series of gaffes, including one during a televised debate when he couldn't remember the name of the third Cabinet department he pledged to eliminate.
Former Pennsylvania Sen. Rick Santorum, a champion of the anti-abortion issue, is still in the race and over the weekend was endorsed by a group of evangelical leaders.
Santorum got some help when the Iowa Republican Party said he bested Romney's eight-vote victory by 34 votes in the caucus.
Gingrich and Santorum are battling to be the anti-Romney choice for conservative voters.
At Thursday's debate, Romney stuck to his strategy of attacking President Barack Obama.
"This president is the biggest impediment to job growth in this country, and we have to replace Barack Obama to get America working again," Romney said.
Gingrich's campaign released his tax returns Thursday, ramping up the pressure for Romney to do the same.
"When they're completed this year in April, I'll release my returns in April, and probably for other years as well," Romney said.
The Associated Press contributed to this report.
