“We had about nine open investigations of classified leaks in the last three years; we have 27 investigations open today,” Mr. Sessions said. “We intend to get to the bottom of these leaks. I think it has reached epidemic proportions. It cannot be allowed to continue and we will do our best effort to ensure it does not continue.”

In August, Mr. Sessions had told reporters that the Justice Department was pursuing three times the number of leak investigations as were open at the end of the Obama administration, but he had declined then to say what the specific numbers were.

(The numbers were also complicated by the fact that the department’s method of tracking such cases conflates leaks to the news media with other types of unauthorized disclosures, like foreign espionage. Mr. Sessions said in August, and again on Tuesday, that there have been four such indictments this year, but only one of those — the charging of Reality Leigh Winner, a contractor working for the N.S.A., with sending an intelligence report about Russia’s interference in the 2016 election to The Intercept — is a classic news media leak case.)

Later, Rep. Jamie Raskin, Democrat of Maryland, brought up Mr. Trump’s accusation that the press is the “enemy of the people,” said the Founders thought the free press was society’s best friend, and asked Mr. Sessions to commit to not prosecuting “investigative journalists for maintaining the confidentiality of their professional sources.”

(That question garbled or conflated two different issues. One is whether journalists could be jailed for contempt if they refuse to provide witness testimony when subpoenaed in connection with an investigation into or prosecution of their suspected sources. The other is whether journalists could be prosecuted as alleged co-conspirators in a criminal leak.)

“I’ll commit to respecting the role of the press and conducting my office in a way that respects that,” Mr. Sessions responded. “We have not had a conflict in my term in office yet with the press but there are some things the press seems to think they have an absolute right to.” but it does not, he added.

He offered no further details about where he draws the line.

A Republican-Sessions divide on government surveillance.

While the Trump campaign contacts with Russia is the main recurring theme, a separate subplot has emerged: surveillance.