The reaction to the assessment by intelligence agencies that Russia sought to promote the candidacy of Donald J. Trump has been mixed. Mr. Trump has seen it as undermining his electoral victory and ridiculed the agencies, accusing them this week of using leaks to discredit him after it briefed him on a dossier of unsubstantiated reports of compromising personal information the Russians allegedly collected.

But on Friday, Senator Richard M. Burr of North Carolina, the chairman of the Intelligence Committee, and the panel’s vice chairman, Senator Mark Warner, Democrat of Virginia, announced that the committee would hold hearings on the Russian activity and its effect on the election.

Before Russians were an issue, there was the F.B.I. investigation into whether Mrs. Clinton or her aides mishandled classified information that was in emails on a private server she was using.

Mr. Comey discussed the investigation and sharply criticized Mrs. Clinton at a news conference announcing that no charges would be brought against her. He also wrote two letters near the end of the campaign that Clinton supporters say cost her the election. But Mr. Comey has not publicly commented on whether there are any open investigations of Mr. Trump or anyone associated with his campaign.

Democrats said the closest Mr. Comey came on Friday to offering an explanation for his actions was to say he would only disclose an ongoing investigation if the public had an overwhelming need to know about it or if it was obvious there was one underway. He said he did not believe any possible investigation into Trump or his associates met either standard.

The F.B.I.’s position is that it does not discuss counterintelligence investigations that could compromise important methods and sources.

Speaking to reporters afterward, Ms. Pelosi said that “really, the American people are owed the truth.”