Former C.I.A. Chief Tells of Concern Over Possible Russia Ties to Trump Campaign

“It raised questions in my mind about whether Russia was able to gain the cooperation of those individuals,” he said, adding that he did not know whether the Russian efforts were successful.

He added, “I don’t know whether such collusion existed.”

It was the first time he publicly acknowledged that he was concerned about possible ties between Russia and the Trump campaign.

He said he left office in January with many unanswered questions about the Russian influence operation. Intelligence officials have said that Russia tried to tip the election toward Mr. Trump.

Mr. Brennan became so concerned last summer about signs of Russian election meddling that he held urgent, classified briefings for eight senior members of Congress, speaking with some of them over secure phone lines while they were on recess. In those conversations, he told lawmakers there was evidence that Russia was specifically working to elect Mr. Trump as president.

Mr. Brennan was also one of a handful of officials who briefed both President Barack Obama and Mr. Trump in January on a broad intelligence community report revealing that President Vladimir V. Putin of Russia had personally ordered an “influence campaign” targeting the presidential election.

— Matt Apuzzo

Watch the hearing, here: