In 1997, a House ethics committee published a long-awaited report on allegations against House Speaker Newt Gingrich, ultimately leading to a $300,000 fine and an embarrassing reprimand two years before he left office.

That was the first time that a House speaker had ever been fined, and it led to Gingrich's leaving Congress four years after orchestrating a dramatic Republican takeover of the lower chamber. More than a decade later, as Gingrich runs for president, his  history has Republicans questioning  whether he's the one for the job he seeks.

Mitt Romney, whose status as the Republican front-runner slipped after he lost  to Gingrich in South Carolina Saturday,  suggested that there's more to the story. He warned Monday that if Gingrich was the nominee, "we could see an October surprise a day.

"Let's see the records from the ethics investigation," he said. "Let's see what they show."

The ethics report was prompted by claims from Democrats that Gingrich had been using a college course  he taught to further a Republican agenda, all the while acting as a tax-exempt entity that could take donations. In a meeting with  counsel for the ethics committee, Gingrich insisted that he didn't have to explain  his intention for the course, as long as it was nonpartisan.

"I don't believe I had an obligation to tell the ethics committee what my political strategies were," he said, according to the committee's report. "I think that's a retrospective comment. And maybe I am wrong.

"If I had wandered around and said to people, 'Hi, we are going to win control, reshape things, end the welfare entitlement, form a grand alliance with Bill Clinton, who is also going to join us in renewing America,' how would I have written that?" Gingrich said.

The House ultimately determined that Gingrich had done wrong, and the extensive ethics report was made public.

To hear Romney tell it, Gingrich is still hiding something. Former House Speaker Nancy Pelosi  said she's got "a lot" on Gingrich, and that "one of these days we'll have a conversation" about him - a comment that Romney has used to predict that "it's going to get out."

Whatever "it" is.

The committee's report is long and thorough, and it contains a lot of stuff that might not  make Gingrich look good. But its contents has  been out there for years, and people familiar with it say it's highly unlikely that a more damaging piece of information is still being kept secret.

The committee, comprising five Republicans and five Democrats, determined in its report that Gingrich repeatedly "showed a disregard and lack of respect for the standard of conduct that applied to his activities." It also punished Gingrich for giving false information to the committee.

"The subcommittee found that in regard to two projects, Mr. Gingrich engaged in activity involving 501(c)(3) organizations that was substantially motivated by partisan, political goals," the report says. "The subcommittee also found that Mr. Gingrich provided the committee with material information about one of those projects that was inaccurate, incomplete and unreliable."

It is true that every single paper related to the ethics committee's investigation hasn't been released. Those are kept private, and not even Gingrich himself would have the authority to let them be seen, as Romney has demanded, according to people familiar with the report.

In that sense, Romney's allegation - that Democrats could get their hands on never-before-seen intel on Gingrich - is more powerful if it remains unanswered, because the likelihood of any new explosive allegations is small.

"The committee cannot release any of those papers," said a former Republican member of Congress who worked on the report in the 1990s. "It would not be right to pound him on something where he has no ability to defend himself.

"He thinks that there's a report," the Republican said of Romney. "But when you have a hearing like that … the final report is made public. And the final report is public, and all the testimony and discussion is on the record and public."

The other question that the ethics redux raises is whether such an arcane process from 15 years ago will matter with today's voters. Gingrich has masterfully countered attacked, most recently by using a revealing interview given by his ex-wife as an opportunity to whip the mainstream media, and shortly afterward to dominate the South Carolina primary.

Romney's decision to purposefully bring up the ethics report reflects his campaign's acknowledgment that Gingrich is a force to be reckoned with in the early primary states. Democrats, meanwhile, haven't strayed one degree from their goal to derail Romney's bid for the nomination.

"I think Mitt Romney's just throwing everything against the wall right now hoping that some of it sticks," said James Thurber, a former congressional aide who has spent years working on ethics and lobbying reform. "The details of the ethics committee probe, and what was found, is very complex, and I don't think it sticks."