Newt Gingrich’s ex-wife Marianne wants to remind America that her former husband is a cad and a hypocrite. In an interview with Brian Ross to be broadcast on Nightline Thursday night, she recalls that Gingrich asked for an open marriage, demanding that she “share” him with Callista, his then mistress, now wife. Speaking to The Washington Post today, she recalled that the next day, he gave a speech titled “The Demise of American Culture,” lambasting liberal disregard for family values. “How could he ask me for a divorce on Monday and within 48 hours give a speech on family values and talk about how people treat people?” she asked.

Unfortunately for Gingrich’s rivals, nothing here is new. John Richardson reported it all and more in his blockbuster 2010 Esquire profile, including the part about Gingrich asking Marianne to simply tolerate his affair. Gingrich’s supporters have already worked through it and either have forgiven him or rationalized it away. That’s why I strongly suspect that Marianne Gingrich’s story, damning as it seems to many of us, won’t hurt him much when South Carolina votes Saturday.

Right now, Gingrich is surging because voters think he can put Obama in his place. At a packed, exuberant rally at Mutts BBQ in ultraconservative Pickens County yesterday, several people told me they made up their minds after seeing him stand up to Juan Williams on the question of putting poor schoolchildren to work as janitors. “They all have baggage, but he just makes sense,” a retiree named Byron Whitehead told me. “How could anybody not listen to the debates and say they don’t believe in Newt?”

Speaking to the crowd, Gingrich repeated a line he’s been using again and again on the stump, saying that he’d challenge Obama to seven three-hour Lincoln-Douglas-style debates, “and I will concede in advance that he can use a teleprompter.” Central to Gingrich’s appeal is the assumption that Obama, being an intellectual lightweight, is scared of him.

It’s likely that the sudden appearance of Marianne Gingrich will only strengthen this belief. After all, much of the right is convinced that mainstream journalists are engaged in a long-term pro-Obama conspiracy. Thus, if they’re attacking Gingrich now, it suggests that he’s a genuine threat to the president’s reelection. “Everybody has an angry ex-spouse,” Rush Limbaugh said on his radio show Thursday. “I don’t know how many people are going to get mad at the media for this, how many people are going to get mad at Marianne Gingrich. I have no clue.” On Fox News, Megyn Kelly said that “there will be questions raised by the American people about the timing of the interview, the timing of its release, and about Marianne Gingrich’s credibility.” Now, a vote for Gingrich isn’t just a vote against Romney. It’s also a vote against the mainstream media, and that’s something the right abhors more than infidelity.