"I honestly never thought these words would come out of my mouth, but I don't know whether the current president of the United States was with prostitutes peeing on each other in Moscow in 2013", Comey told ABC.
It's the first sit-down, televised interview Comey has given since he was sacked by President Donald Trump previous year and the first in a series of interviews he will sit for in the coming weeks.
Trump also tweeted that Comey's mishandling of the Clinton email probe deserves "jail" time and called him a "slimeball".
Comey's new book, replete with highly unflattering characterizations of Trump, is garnering wide attention in advance of its release.
That didn't sit too well with the President, who suggested Comey was looking for a gig in the Clinton administration.
"Wasn't the decision to reveal influenced by your assumption that Hillary Clinton was going to win, and your concern that, she wins, this comes out several weeks later and then that's taken by her opponents as a sign that she's an illegitimate president?", Stephanopoulos asks.
Mr Ryan, asked whether Mr Comey was a man of integrity, said, "as far as I know" but added that he did not know him well. Conservatives cried foul, insinuating there was something corrupt about the meeting, which Clinton and Lynch said was largely friendly talk about their grandchildren.
The Washington Post has a thorough rundown of the many mistruths and unproven assertions Trump packed in to just seven fewer-than-280-character bursts. "His memos are self serving and FAKE!" he said. "Two or three briefings is about what I had with James Comey", Ryan, who announced his retirement last week, told NBC's Chuck Todd on "Meet the Press".
Third, Trump gets into his claim that there's a partisan conspiracy working against him - claiming former FBI Deputy Director Andrew McCabe is corrupt, and that this is all somehow actually Hillary Clinton's fault.
Mrs Clinton blames his decision to reopen the email probe 11 days before the 2016 election for her surprise defeat. While Comey does not outline the details of the information - and says he didn't see indications of Lynch inappropriately influencing the investigation - he says it anxious him that the material could be used to attack the integrity of the probe and the FBI's independence.
Trump on Sunday revived the tarmac conspiracy, asking what happened between "Wild Bill" and Lynch.
"Comey throws AG Lynch "under the bus!"
Mueller is looking into whether Trump has sought to obstruct the Russian Federation probe, and Comey could be a key witness on that front.