The biggest political happening today is not the GOP debate. Not even close. It is the anticipated ABC interview with Newt Gingrich’s ex-wife Marianne. It was teased on the Drudge Report last night with the suggestion that there had been a battle within the network as to when to air it. It will air tonight on ABC’s “Nightline,” making the debate a weird warmup for the main event. In an attempt to soften the blow, the Gingrich campaign released a letter signed by his two daughters from wife No. 1. It tried to plead that in essence this was old news and a private matter:

The failure of a marriage is a terrible and emotional experience for everyone involved. Anyone who has had that experience understands it is a personal tragedy filled with regrets, and sometimes differing memories of events.

We will not say anything negative about our father’s ex-wife. He has said before, privately and publicly, that he regrets any pain he may have caused in the past to people he loves.

ABC News or other campaigns may want to talk about the past, just days before an important primary election. But Newt is going to talk to the people of South Carolina about the future. . ..

But, of course, Gingrich’s behavior in office put himself and his party at risk. The issue isn’t a failed marriage; it is whether his character is so flawed as to disqualify him from the presidency.

You can bemoan the timing of the interview, just days before the election. But if ABC held the piece it would have been bashed for withholding information critical in deciding vote.

In 2010 Marianne gave an interview with tidbits about Gingrich’s request for a divorce (he had already asked Callista to marry him), his ethics fiasco and his fall from the speakership. The media are inured to it all because they’ve heard it so many times or witnessed it themselves. But there’s quite a difference between vaguely knowing that he had a series of wives and being presented with the details. In particular, his recklessness in carrying on an affair with Callista at the very time he was pursuing Bill Clinton’s impeachment in the Monica Lewinsky scandal will rankle some voters. At the very least it’s going to make those values voters very uncomfortable. And needless to say, if Gingrich has a good debate performance he’s going to get upstaged by his ex-wife.

We shouldn’t be surprised that Marianne has stepped forward. Indeed, how many other friends, staffers and colleagues have their own tales to tell about the speakership years? With Gingrich you are perpetually waiting for the next shoe to drop. And unlike Bill Clinton, who could drag Hillary into the picture for validation and redemption, Gingrich can’t very well sit down with Callista to explain their joint tale of deceit and adultery.

This, of course, is the argument against Gingrich that Rick Santorum and Mitt Romney have implicitly raised: With Newt, it is always about him. The party (should he be the nominee) and the country (should he make it to the Oval Office) would be at the mercy of his whims, his rhetoric and his undisciplined intellect (in which speed and quantity overwhelm good judgment and quality). He’s the Pigpen of politics, surrounded by a cloud of dust of his own making.

As is Gingrich’s style, you can bet he will claim martyrdom on this, rail at the mainstream media for bringing it up just before the election and contend he is being brought down because the “establishment” is afraid of him. Puleez. The origin of every Gingrich controversy (ethical, personal or political) is the same: Huge ambition unmoored to a code of conduct or fixed principles.

The reemergence of Marianne will give voters pause. It should. And if it’s the difference between victory or defeat in South Carolina? Well, some would call that Gingrich’s just desserts.