“Is it possible that all of these events and reports are completely unrelated and nothing more than an entirely unhappy coincidence?” Mr. Schiff asked. “Yes, it is possible. But it is also possible, maybe more than possible, that they are not coincidental.”

Republicans seemed much less interested in the answer.

The effort to change the subject began with Mr. Trump, who said on Twitter early Monday that the “real story” is the “leaking of Classified information.” Later, he asked: “What about all of the contact with the Clinton campaign and the Russians?”

At the White House, Sean Spicer, the press secretary, returned to the subject of leaks again and again during his daily briefing for reporters, echoing the Republican lawmakers from the presidential podium.

Mr. Spicer railed against the “illegal leak” of the names of some of Mr. Trump’s associates under investigation. And he insisted that news organizations are refusing to cover the real story from Monday’s hearing: the need for the federal government to stop national security leaks.

Mr. Spicer also evaded questions about Mr. Trump’s associates by repeatedly returning to what he said were Hillary Clinton’s ties to Russia, even though Mrs. Clinton’s presidential campaign was hurt by Russian operatives’ hacking.

Mr. Spicer accused journalists of ignoring stories alleging that the Democratic National Committee had not provided the F.B.I. access to its hacked servers, a claim Democratic officials deny. Mr. Comey said Monday that the investigators got the information they needed to investigate the hack.