“Newt,” Mr. Frank says today, “is the single most influential factor in replacing the politics in which you accepted the bona fides of your opponents and disagreed with them civilly with the politics of insisting that your opponents are bad people.”

Mr. Gingrich has said he was on a mission to “repair the integrity of the House,” but critics are skeptical. Fred Wertheimer, then the head of Common Cause, says Mr. Gingrich saw ethics charges as “a vehicle for destroying the House as an institution and taking over what was left.”

But Steven M. Gillon, a University of Oklahoma historian who has written a book about Mr. Gingrich and Mr. Clinton, offers another explanation. Southern Republicans in the post-civil rights era often used race as a wedge issue, Mr. Gillon said. But Mr. Gingrich, a one-time Rockefeller Republican who embraced integration, needed a different line of attack. “He needed to find a wedge that would undermine the moral credibility of the Democratic Party,” Mr. Gillon said, adding, “He could use ethics as sort of a bludgeon, and that’s what he did.”

Empty House, Big Microphone

Mr. Gingrich’s arrival in Congress coincided with the rise of C-Span, the cable channel that televised House proceedings, and he figured out early on how to combine his gift for oratory with the power of the camera. Night after night, he would lambaste Democrats, speaking in an empty House chamber after the day’s legislative business was done. Mr. Gingrich would needle Democrats, challenging them to come forward and defend themselves. No one did, because no one was there.

Things came to a head in May 1984, on a day when the chamber was full. Mr. Gingrich had been pounding a group of Democrats over a letter they had written to Daniel Ortega, the Nicaraguan leader, accusing them of spreading “communist propaganda.” Thomas P. O’Neill Jr., the House speaker, let loose.

“You deliberately stood in that well before an empty House, and challenged these people, and challenged their Americanism,” he roared, wagging his forefinger at Mr. Gingrich, “and it’s the lowest thing I’ve ever seen in my 32 years in Congress.”

It was a rare breach of decorum; Mr. Gingrich had gotten the better of Mr. O’Neill. House rules forbid personal insults, so Mr. O’Neill’s words were “taken down”— stricken from the record, a rare rebuke and a turning point, many here say, in relations between Republicans and Democrats.