GREENVILLE, S.C. — While Newt Gingrich was onstage Wednesday night at the Pro-Life Presidential Forum here, journalists in the back of the Hilton Hotel ballroom were learning — via their laptops, iPads, and cell phones — that Matt Drudge had just broken an exclusive story that might completely change the race for South Carolina’s crucial Republican primary.

“NEWT EX-WIFE UNLOADS” was the banner headline, linking to Drudge’s own report that Gingrich’s ex-wife Marianne had given a two-hour interview to Brian Ross of ABC News with “explosive revelations.” According to Drudge, there was a debate about the “ethics” of airing the interview prior to Saturday’s primary vote here, but the Associated Press subsequently reported that ABC is “likely” to broadcast it late Thursday night on the network’s “Nightline” program. According to the Washington Post, an ABC spokesman has indicated the network will release excerpts from the interview during the day on Thursday.

Depending on what that interview contains, its potential to have a last-minute impact on the South Carolina primary results is difficult to calculate. However, no one can doubt that it may devastate Gingrich’s prospects to become the “Anybody But Mitt” candidate whom many conservatives have hoped would prevent the nomination of former Massachusetts Gov. Mitt Romney. And it is just one of many twists and turns in the hard-fought campaign here in the state where Republicans proudly boast, “We pick presidents.”

The effort to stop Romney, the moderate frontrunner, has entered a desperate phase. Gingrich himself said Wednesday that if Romney wins South Carolina, the 2012 primary campaign is effectively over. And the former House Speaker was apparently feeling so confident after his strong debate showing Monday in Myrtle Beach that he was the man to beat Romney here that he suggested that two of his GOP rivals — former Pennsylvania Sen. Rick Santorum and Texas Gov. Rick Perry — should drop out and endorse him, “consolidating into a Gingrich candidacy” for the sake of “the conservative movement.” That was Tuesday and on Wednesday, one of the most vocal early supporters of Perry’s campaign, Erick Erickson of Red State, joined in calling for the Texan to quit the race. A spokesman for Perry dismissed Erickson as “a pundit sitting behind a computer somewhere,” evidently ignoring the fact that Erickson introduced Perry at the governor’s Aug. 13 official announcement of his candidacy in South Carolina, where Perry began his speech by saying, “Howdy. Thank you, Erick.”

Perry is currently dead last in the RealClearPolitics Average of polls in South Carolina, a state where he led by 23 points in one poll taken shortly after he entered the GOP race five months ago. The clear cause of Perry’s downfall was the same factor that has contributed so much to Gingrich’s rise, the televised debates that have exercised such an enormous influence in the long campaign for the Republican nomination. After a series of debate debacles in September, Perry’s support collapsed and, despite the expenditure of millions of dollars by his campaign, he has been unable to recapture any of his once-formidable momentum. Perry was reportedly ready to quit after a fifth-place finish in the Jan. 3 Iowa caucuses, but decided instead to skip the New Hampshire campaign to come to South Carolina and attempt a last stand here. Another embarrassing defeat in Saturday’s vote will almost certainly end his campaign, which was why both Erickson and popular conservative talk-radio host Laura Ingraham on Wednesday called for him to drop out and endorse Gingrich before the primary.

That seems unlikely, given that Perry has in recent days made pointed references to the Alamo, where Texans famously fought to the death. Yet the “Anybody But Mitt” conservatives expressed concern that Perry might in effect play the role of a spoiler in the Palmetto State, draining away enough votes to enable Romney to score a decisive victory. And the man suggested as the only hope to stop Romney — not only by Erickson and Ingraham, but also in an almost-endorsement Tuesday by Sarah Palin — is Gingrich, whose campaign suddenly seems at risk from his ex-wife’s interview with ABC News.

As of Wednesday evening, there were no details of what Marianne Gingrich told ABC’s Ross, but it serves as a reminder of the thrice-married former House Speaker’s controversial past. His current wife was a congressional staffer when Gingrich began an affair with her while he was still married to Marianne, and that affair occurred even while Gingrich was leading House Republicans to impeach President Clinton over his affair with Monica Lewinsky. Thus, his second wife’s TV interview would fit with the theme of an ad that a pro-Romney “super PAC” is airing in South Carolina and Florida, which says “Newt… has more baggage than the airlines.” Gingrich’s baggage problem was clearly in the mind of one South Carolina voter Wednesday night.

“Newt is really his own worst enemy,” said Cliff Poynter of Greer, S.C., who joined his two adult sons for a late-evening meal at a McDonald’s in Greenville. “He’s a tremendous debater and a brilliant thinker with a flawed character. If the Republicans are going to beat Obama, the election has to be about Obama and his policies. But if Newt becomes the nominee, it’s going to be easy for the Democrats to make it about Newt, his past and his lack of character.”

Poynter described himself as “very pro-life,” adding that he married his high-school sweetheart 37 years ago and they have five children, and expressed his support for Santorum. Unlike Gingrich, Santorum has downplayed suggestions that the GOP battle will end if Romney wins here, insisting that he’s prepared to make a long-term campaign for the nomination, whatever the odds against him or whatever the result on Saturday. While Santorum has apparently lost some of the surging momentum that enabled him to battle Romney to a draw in Iowa, he continues to urge voters to “stand up and fight” for their conservative convictions.

There will be another debate tonight, in Charleston (8 p.m. ET on CNN), and it remains to be seen if the last-minute developments will reshape the results in the state that has voted for the eventual Republican nominee in every primary since South Carolinians voted for Ronald Reagan in 1980.