The prospect of a new round of perjury accusations from Congress has underscored that the furor over the leak investigations might pose a new threat to Mr. Holder, who surprised many Democrats by choosing to stay on after Mr. Obama’s re-election. For now, Democrats on the House Judiciary Committee are standing by Mr. Holder, even though the ranking member, Representative John Conyers Jr. of Michigan, pronounced himself “deeply troubled” by some of the investigative tactics used in recent leak cases.

“Certainly, it is fair to ask additional questions about the Rosen investigation, and any role the attorney general may have played in it, but I do not believe it credible to level charges that he may have intentionally misled the committee on this matter before we know the facts of the case in question,” Mr. Conyers said.

In his only recent interview, Mr. Holder told The Daily Beast that the investigations obeyed existing laws and guidelines, but he also said the rules “need to be updated.” He called the furor “an opportunity for the department to consider how we strike the right balance between the interests of law enforcement and freedom of the press.”

The Daily Beast article also paraphrased unnamed aides as saying Mr. Holder was “also beginning to feel a creeping sense of personal remorse.”

Reid Weingarten, a lawyer who has been a friend of Mr. Holder’s for three decades, said Mr. Holder had discussed no such feelings with him. Rather, Mr. Weingarten said, the disclosure to Fox News of the existence of a rare intelligence source in North Korea was “a horrible leak and he was charged with the responsibility to get at it.” That raised what he said Mr. Holder described to him as a trade-off between press freedoms and the need to identify leakers — a problem for which there are no easy answers because it pits “two laudable goals” against each other.