Transcript for Gingrich Ex: Newt Wanted 'Open Marriage'
This story at the white hot intersection of presidential politics private lives and character. Former speaker of the house Newt Gingrich is surging in South Carolina where voters go to the polls Saturday. Gingrich has been in the public eye for decades and he's had a complicated private life he spoken openly about that life on the campaign trail. Admitted wrongdoing has said he sought forgiveness and reconciliation. His two ex wives have stayed quiet on the sidelines. Tonight ABC's Brian Ross investigates Brian. -- tonight one of them is breaking her silence his second wife Marianne saying she does not believe Gingrich as the moral character necessary to be precedent. Marianne Gingrich is married to nude for eighteen years when he Astor for a divorce. It started with a phone call. At my mother's house and -- asked for divorce. And on the phone on the phones and he said I want and reports. I said is that somebody else. And with quiet. And I knew. Now twelve years later Marianne Gingrich is talking on television for the first time. I kind of January surprise for her ex husband he faces a crucial presidential primary in South Carolina the -- If he's running for president he -- -- -- You know his secrets. You know -- skeletons I know some of them. Gingrich is now married to that somebody else the other woman Calista. Devout Catholic who is -- she was -- mistress for some six years while he was still married to -- I found that during our conversations. But it was occurring in my bedroom in our apartment in Washington. And he always called me at night he would always ended with I love you. Well she was there -- list. Right next to him in my home. Washington is a place full of two timing politicians with a long trail of sordid affairs ugly divorces and hypocrisy. And as speaker of the house in the middle of his own secret affair with Calista. Gingrich was calling for the impeachment of President Bill Clinton for lying about his affair with Monica Lewinsky. There is no administration American history with less moral authority than the Clinton gore administration. Now as a candidate for president. Gingrich regularly expound on family -- was and the sanctity of marriage between a man and a -- And is something worth protecting and upholding. But he is also freely admitted to his moral theories I've set up front openly I've made mistakes at times -- had to go to god for forgiveness. And had to seek reconciliation. Marianne says Gingrich has never asked her for forgiveness. And that when first seeking a divorce -- actually asked her for an arrangement under which she could have both a wife and a mistress. I said to him. -- we've been married a long time. And he said. Yes but you want me all to yourself. Calista doesn't care what -- you know. Who was saying to use it while he was asking to have an open marriage and I refused. He wanted an open marriage -- that I accept the fact that he he has somebody else that has. And you said. Now. Now. That is -- -- Mary X. Gingrich asked for -- divorce from his first wife Jackie while she was being treated for cancer. He sought to divorce Marianne she says months after she was diagnosed with multiple sclerosis MS. Did he know. Unanimous. Yes. When he asked if true source yes and he also was advised by the doctor when I was sitting there I was not to be under stress. And during tonight's CNN debate in South Carolina. First question of the heat was about the open marriage allegation. Gingrich angrily denied cheers from the -- New shows to start the debate with a don't try to blame somebody else. You -- your staff chose to start yesterday. -- -- The story is false. Every personal friend I have who -- less and -- Prius is a story was false earlier in the campaign also made available his two daughters from his first marriage. Them. To the -- Brian is that. Our father and Maryanne had a difficult marriage they had a difficult divorce she's unhappy. And on this has -- over over for over decades he's a much different person. Then he was then he's grown he's gotten closer they got a -- and got his current. -- and I think what people need to remember is this having a very long time ago and we you know we wish Marion no -- well we -- the very best. But it happened long time of them. Marianne Gingrich says she does have many fond memories of new holding hands on -- all hiking in the mountains dressing up on Halloween. A time when she says they were without power are much Monday. To that create a desire to get rich. I think we always top of that. Money would come when he left congress. Was young woman from Georgia please -- it right here. But while still in congress as Gingrich became speaker of the house they traveled the world even as he and she were caught up in several ethics investigations. On this issue. Marianne defends her -- house. Is an ethical man. At the time I believe him to be ethical. Marianne herself became the subject of an FBI sting investigation. After meeting in Paris with a notorious arms -- Who was working as an undercover government source the investigation was ultimately dropped. But a 1997. FBI document obtained by ABC news says. Gingrich told the source that she was in a position to get things done in congress. And asked for 500000. Dollars for herself up front. As part of an alleged ten million dollar bribe to buy influence with her husband the speaker of the house. This is all made. Fabricated. -- -- this is a convicted felon. Talking with people that have nothing to do with me -- you met them. I did meet with him. It would cost ten million dollars to get the job done the could. -- -- did you ever try to tell her husband's position. Happens narrow. Newt Gingrich lost his power as speaker of the house and resigned from congress in 1998. A year later he asked for divorce. And says -- began to plan his campaign to run for president with Calista by his side. Who is probably best known in this campaign but the hundreds of thousands of dollars worth of jewelry Gingrich bought for her at Tiffany. He did tell me -- That. She was going to help him become parents. Who was your reaction to that. -- look like help to me. We asked the Gingrich campaign if he would appear tonight in our report but they declined to make them available. Following Gingrich is strong denial to not of the open marriage allegations I checked back with a -- wife Marianne who told me by phone she stands by her story. My story is the troops utility if he had really changed he could have stepped up tonight and said he was sorry but he never had so that is. Maria tonight and a tough one it is -- and as you know this story has sparked a lot of controversy. And tonight at that CNN debate in South Carolina Newt Gingrich spoke out passionately about it but the whole subject. After moderator John King had made at the focus of his first question. I think it is -- Steve 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 the you would Begin a presidential debate. On a topic. To take an ex wife. And make it two days before the primary. A significant question -- presidential campaign. Is as close to dispensable. As anything I can imagine. I.
This transcript has been automatically generated and may not be 100% accurate.