Two days out from the South Carolina primary, Newt Gingrich’s past is haunting him like never before.

View Photo Gallery: The former House speaker is seeking the Republican presidential nomination.

There was the news Thursday morning that Gingrich’s former wife, Marianne, is going public with some of the private details of her 18 years with the candidate, including the former House speaker’s alleged request for “an open marriage.”

And now, one of Gingrich’s former House colleagues is stepping up his criticism of the candidate on behalf of the Romney campaign, reminding voters of Gingrich’s tumultuous speakership and past ethics troubles.

“We had ... obviously well over 218 Republicans in the Congress when Newt was the speaker, and you can’t find more than a handful who will come to his defense,” House Homeland Security Chairman Peter King (R-N.Y.) said Thursday morning on a conference call organized by the Romney campaign.

“And it has nothing to do with ideology, nothing to do with philosophy. It’s all the erratic, self-serving narcissism of Newt.”

The Gingrich campaign has not yet responded to a request for comment.

King, who served with Gingrich in the House for six years from 1993 to 1999, was joined on the call by former New Hampshire governor and White House chief of staff John H. Sununu, another prominent Romney backer.

“I’m one of those people who served with Newt Gingrich in Congress and I will say up front that Newt was responsible for us winning back the House in 1994, but after that, it was just a series of self-induced wounds,” King told reporters. “The Republican Party, for the four years that he was the speaker, we went from crisis to crisis and there’s enough real crisis in government, and, if you’re president, there’s enough crisis in the world without constantly manufacturing crisis of your own.”

The two lambasted Gingrich’s record as speaker, arguing that if Gingrich were to win the GOP nomination, the White House would have plenty of ammunition to use against him, including details from the ethics probe launched against him by the House in the late 1990s.

“The point is that there was a 7-to-1 vote in that ethics committee, which means the material was pretty convincing, even to the 4 Republicans, 3 of which against him,” Sununu said, referring to the House Ethics Committee’s January 1997 vote to recommend that Gingrich be reprimanded by the full chamber. The lone “no” vote on the panel was cast by Rep. Lamar Smith (R-Texas).

Gingrich was reprimanded by the House in 1997 and was ordered to pay a $300,000 fine for violating the chamber’s rules.

Sununu argued that Gingrich “ought to ask for the release of the complete records of the ethics process and get that out in public so that he doesn’t become a vulnerable candidate if he wins the nomination and doesn’t become vulnerable to an October surprise.”

“I think it reflects on his reliability as a leader, and frankly ... whatever Congresswoman Pelosi knows, President Obama knows,” Sununu said. He added that “we ought to at least wring out the laundry now.”

King recalled Gingrich’s now-infamous remark that he had been relegated to the back of Air Force One by President Bill Clinton on the trip to and from Israel to attend the funeral of Prime Minister Yitzhak Rabin, a perceived “snub” that Gingrich said at the time contributed to the 1995 federal shutdown.

“Now, that’s bad enough -- he made himself look foolish -- but he cost us that whole battle with Bill Clinton over the government shutdown that was going on,” King said Thursday. “And the way he was portrayed was we shut the government down because Newt Gingrich had to get off the back of Air Force One.”

“We can go on with so many stories like that,” King added.

Sununu also returned to the issue of Gingrich’s consulting work for Freddie Mac. Gingrich has defended his tenure at the mortgage giant, arguing that he was a “historian” and not a lobbyist.

“Even though he says he was not a lobbyist, I suspect that there’s something in there that at least indicates he might have been a lobbyer without being a lobbyist. ... I just want to emphasize that the issue now is electability,” Sununu said.

Asked whether those who served together with Gingrich might be coming out now and attacking the candidate because they had an axe to grind, King dismissed the idea.

“This is not a faction of the party coming after him,” King said. “This is not a wing of the party; it’s not a region coming after Newt. It’s a cross-section of those who worked under him who are not even questioning his ideology -- because sometimes you can’t even figure out what it is anyway -- but the fact is the lack of stability, the unreliability and, again, when confronted, Newt’s immediate thing is to say people were trying to avenge the past or whatever.”

According to a list maintained by Roll Call, Gingrich has 11 congressional endorsers, including two – Reps. Joe Barton (R-Texas) and Jack Kingston (R-Ga.) – who served in the chamber at the same time as Gingrich.