CHARLESTON, S.C. — Presidential contender Newt Gingrich on Thursday angrily denied that he asked his second wife for an "open marriage" that would allow him to have a mistress as she claims in an interview broadcast two days before the South Carolina primary.
"Let me be quite clear. The story is false," Gingrich said at a debate, without elaborating.
At the same time, his campaign released his tax returns, showing that he paid more than $994,000 in federal taxes on more $3.1 million in income in 2010.
It was a day of ups and downs for Gingrich, who picked up the endorsement for former rival Texas Gov. Rick Perry. The former House speaker is working to consolidate the support of conservatives behind his candidacy with polls showing him rising in his bid to overtake Republican front-runner Mitt Romney.
"Newt is not perfect but who among us is," Perry said as he bowed out of the race, seeking to provide Gingrich with some political cover in a state filled with evangelicals likely to cringe at Gingrich's two divorces and acknowledged infidelity.
Gingrich's ex-wife threatened to throw his campaign off course.
In excerpts the network released earlier in the day, Marianne Gingrich told ABC News in an interview being broadcast late Thursday that when she discovered Gingrich was having an affair with Callista Bisek, a congressional staffer, he asked his wife to share him.
"And I just stared at him, and he said, 'Callista doesn't care what I do,'" Marianne Gingrich told ABC News. "He wanted an open marriage, and I refused."
She confirmed to The Associated Press that the former speaker had asked her for an open marriage, but she refused his request. She declined to comment further.
At the debate Thursday, Gingrich forcefully denied his ex-wife's charges and castigated debate moderator — CNN's John King — for raising the issue at the start of the two-hour long event.
"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," Gingrich said. "And I am appalled that you would begin a presidential debate on a topic like that."
As he stood on stage in Charleston, his campaign released his 2010 income tax returns, which showed he paid roughly 31.6 percent of his adjusted income in taxes, giving about 2 percent to charity. Gingrich criticized rival Romney — who is worth more than $250 million — this week for saying he paid only 15 percent.
Gingrich gave $81,133 in cash or checks to charities, about 2.6 percent of his income. That is considerably less than the average of $259,692 that households earning at least $2 million a year gave to charities in 2009, according to research from the Center on Philanthropy at Indiana University.
Personal financial disclosure forms filed last summer show Gingrich is worth more than $6.5 million. He reported at least $500,000 in assets from Gingrich Productions, his media company that produces books and films.
Two days before the pivotal South Carolina primary, Gingrich's political and private life were clashing just as new polls showed him rising as he looks to overtake Romney in the third state to weigh in on the presidential race. Gingrich has seen his crowds grow in recent days after a strong performance in a debate Monday.
It was unclear how the new revelations from Marianne Gingrich would play in a state where religious and socially conservative voters hold sway. The interview's mere existence shines a spotlight on a part of Gingrich's past that could turn off Republican voters in a state filled with religious and cultural conservatives who may cringe at his two divorces and acknowledged marital infidelities.
Marianne Gingrich has said Gingrich proposed to her before the divorce from his first wife was final in 1981; they were married six months later. Her marriage to Gingrich ended in divorce in 2000, and Gingrich has admitted he'd already taken up with Bisek, the former congressional aide who would become his third wife. The speaker who pilloried then President Bill Clinton for his affair with Monica Lewinsky was himself having an affair at the time.
Earlier in the day, a Gingrich spokesman suggested, like Gingrich's daughters did a day earlier, that Marianne Gingrich's comments may be suspect given the emotional toll divorce takes on everyone involved.
"Divorces are very tough and people have very different recollections of how things happen," R.C. Hammond said.
Equally uncertain was whether Gingrich would get a boost from Perry's endorsement, given that the Texas governor had little support in the state, and get conservative voters to coalesce behind his candidacy. Complicating Gingrich's effort is another conservative, Rick Santorum, who threatens to siphon his support.
A CNN/Time South Carolina poll released Wednesday showed Gingrich in second place with support from 23 percent of likely primary voters, having gained 5 percentage points in the past two weeks. Romney led in the poll with 33 percent, but he had slipped some since the last survey. Santorum was third, narrowly ahead of Texas Rep. Ron Paul and well ahead of Perry.
Regardless of the South Carolina outcome, Gingrich was making plans to compete in Florida's primary on Jan. 31.
Confidence exuded from Gingrich, who rose in Iowa only to be knocked off course after sustaining $3 million in attack ads from an outside group that supports Romney. Gingrich posted dismal showings in both Iowa and New Hampshire.
By the time the race turned to South Carolina, he was back on course — and criticizing Romney as a social moderate who is timid about attacking the nation's economic troubles.
Ray Henry in Atlanta and Jack Gillum in Washington contributed to this report.