1. The fallout from President Trump’s abrupt firing of the head of the F.B.I. dominated a Senate hearing about the biggest security threats facing the United States.

Andrew McCabe, the acting F.B.I. director, above, rejected the White House’s claim that James Comey had lost the support of his colleagues, contradicting the president’s latest explanation for the dismissal.

Mr. McCabe also said that the firing had not affected the Justice Department’s investigation of Russia’s meddling in the presidential election.