"The irony of your making that statement, I cannot avoid," said Sen. Angus King, a Maine independent.
Insisted Sen. Ron Wyden, D-Ore., "The American people have the right to know this."
It wasn't clear if Wyden was alluding to an investigation that may be classified, or if his questioning was an effort to cast Trump in a negative light shortly before the inauguration.
Former Senate Minority Leader Harry Reid, D-Nev., wrote two letters to the FBI last year before the election, asking the bureau to publicly disclose what it knew about Trump's aides' ties to Russia.
An active FBI investigation of the next president for ties between his campaign and a nation accused of meddling in the presidential election could further stoke mistrust in the legitimacy of the democratic process. It could also put Trump's own FBI in the awkward position of examining the conduct of those closest to the commander-in-chief.
The FBI was among three U.S. intelligence agencies that collaborated on last week's report on Russia's election activity. It tied Russian President Vladimir Putin to the hacking of email accounts of the Democratic National Committee and individual Democrats like Clinton's campaign chairman, John Podesta. It said there was no evidence the Russians tampered with vote tallies; the agencies said they couldn't assess if Russia succeeded in influencing Americans to vote for Trump.
Intelligence officials briefed Trump and President Barack Obama on their findings late last week. The New York Times and CNN reported Tuesday night that the officials also presented Trump with unsubstantiated reports that Russia had compromising personal and financial information about him.
Sen. Marco Rubio, R-Fla., who opposed Trump in the GOP primary, said Russia's activity wasn't guided by its support for Trump, but rather "to influence and to potentially manipulate American public opinion for the purpose of discrediting individual political figures, sowing chaos and division in our politics, sowing doubts about the legitimacy of our elections."
Democrats at the committee hearing focused their toughest questions on Comey, who was widely criticized for breaking FBI policy in his decision to notify Congress about additional information that came up related to Clinton. He is in the fourth year of a 10-year term, meaning he is expected to stay on in the Trump administration.
Sen. Kamala Harris, D-Calif., said Comey set a new standard by discussing the bureau's activity related to Clinton's private email server. That standard, she said, is the FBI discusses ongoing investigations when there is a "unique public interest in the transparency of that issue."
The intelligence agencies' findings on Russian hacking fit that standard, she argued.
"I'm not sure I can think of an issue of more serious public interest than this one," Harris said. "This committee needs to understand what the FBI does and does not know about campaign communications with Russia."
Sitting beside Comey, Director of National Intelligence James Clapper said, "Fair point."