Jan. 19, 2012 — -- Newt Gingrich's two adult daughters said that charges by Gingrich's second wife in an interview with ABC News that the GOP presidential contender asked for an "open marriage" are categorically false.
Kathy Lubbers and Jackie Cushman, Gingrich's daughters by his first wife, told ABC News Chief Investigative Correspondent Brian Ross they had spoken with their father about Marianne Gingrich's allegation and that he had assured them he never asked for an open marriage.
"We spoke with him about that, Brian, and he said it's simply not true," said Kathy Lubbers. "The truth is our father and Marianne had a difficult marriage. They had a difficult divorce. ... The American people have moved on. Our father has moved on."
"I think most divorces are very painful, they're never easy," said Jackie Cushman. "Dad tried very hard to make their marriage work, and unfortunately it didn't."
In an interview to be broadcast on "Nightline," her first since her 1999 split from the former Speaker of the House, Marianne Gingrich told Ross that Gingrich sought an "open marriage" arrangement so he could have a mistress and a wife.
CLICK HERE to see a preview of ABC News' exclusive broadcast interview with Marianne Gingrich and then catch the full interview tonight on ABC News' Nightline at 11:35 p.m. ET.
She said when Gingrich admitted to a six-year affair with a Congressional aide, he asked her if she would share him with the other woman, Callista, who is now married to Gingrich.
"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."
Marianne Gingrich, a self-described conservative Republican, said she was coming forward so voters could know what she knows about Gingrich.
On the stump in Beaufort, South Carolina Thursday, Gingrich called his ex-wife's interview with ABC News "tawdry and inappropriate," and would not answer questions about it.
"I'm not going to say anything about Marianne," he said.
Gingrich declined to comment to ABC News for this report, but told NBC's Today Show Thursday morning he would not "say anything negative about Marianne."
"Now, I'll let my daughters speak for it… I'm not going to comment beyond that because I'm focused on the big issues that concern the American people, which are the current challenges we have, largely because of the failure of the Obama presidency," he said.
Lubbers and Cushman said they would not say anything negative about Marianne and said their father "regrets any pain he may have caused in the past to people he loves."
"I know he did try hard for many years to make the marriage work," Cushman told ABC News. "He is a much different person than he was then. This happened a very long time ago."
Marianne Gingrich told Ross during her interview that since her ex-husband is running for president, "he has answers to give."
"Our father clearly has the character needed to lead this country," said Gingrich's daughter, Kathy Lubbers. "And as far as character goes, he has delivered on his promises."