Comey himself suggested during his three-hour sworn testimony that President Donald Trump had a shaky commitment to telling the truth. The White House decried the accusation.
Meanwhile, Trump's outside lawyer insisted that it was Comey who lied when he detailed conversations between himself and the President, raising the suggestion that Comey committed perjury while testifying under oath.
It amounted to one lawyer's word against Comey's, with little indication that the matter will be resolved in the near-term.
Comey told lawmakers during his testimony that Trump wasn't telling the truth when he characterized the FBI workforce as deeply dissatisfied with the former director's leadership.
"Those were lies. Plain and simple," Comey told the Senate intelligence committee.
Later, Comey said he felt compelled to document his meetings with Trump because he was concerned the President would mislead the public about what transpired between them.
"I was honestly concerned he might lie about the nature of our meeting," Comey said.
Trump's spokeswoman reacted fiercely to those statements, insisting the President was a truthful man.
"I can definitely say the President is not a liar, and I think it's, frankly, insulting that question would be asked," spokeswoman Sarah Huckabee Sanders told reporters during an off-camera briefing at the White House.
Hours later, it was Trump's outside attorney Marc Kasowitz lobbing accusations of dishonesty. He said Comey's claims that Trump demanded loyalty during an Oval Office meeting were false.
"The President also never told Mr. Comey, 'I need loyalty, I expect loyalty' in form or substance," Kasowitz said, quoting Comey's account of a meeting between himself and the President in January.
Also false, according to Kasowitz: Comey's allegations that Trump pressured him to end the FBI's investigation into former national security adviser Michael Flynn.
Trump "never, in form or substance, directed or suggested that Mr. Comey stop investigating anyone, including suggesting that that Mr. Comey 'let Flynn go,' " Kasowitz said.
Comey declined to comment on Kasowitz's accusations as he departed Capitol Hill Thursday.
But during his testimony, the former FBI director said he hoped tapes existed of his conversations with Trump since they would prove his version of events.
"Lordy, I hope there are tapes," Comey said.
Back at the White House, Sanders couldn't say whether there are secret recording devices installed in the Oval Office, or other rooms where Trump holds meetings.
"I'll try and look under the couches," she quipped.
Sanders, who briefed reporters as Comey's testimony was entering its third hour, said Trump hadn't watched the event in its entirety. Instead he met with members of his national security team to discuss provocations from North Korea and an unraveling situation in the Arab Gulf.
She declined to answer most questions about Comey's testimony, referring instead to an upcoming statement from Trump's outside lawyer Marc Kasowitz, who is due to update reporters later Thursday.
Sanders instead said that Thursday was just another workday at the White House, even amid Comey's bombshell testimony on Capitol Hill.
"We are carrying on as if we normally would," Sanders said.