Trump fired Comey in May 2017, citing the FBI's behavior in investigating Democrat Hillary Clinton and its probe into possible Trump campaign collusion with Russian Federation to tilt the 2016 presidential election.
In one highlight, Stephanopoulos said: "You write that President Trump is unethical, untethered to the truth".
Comey, fired by Trump in May previous year, was anxious the president may be open to blackmail by Russian Federation given claims he was present when prostitutes urinated on each other during a 2013 Moscow visit.
Asked if the decision to reveal that the FBI was revisiting its investigation into Hillary Clinton's use of a private email server was driven in part by the assumption that she would win the 2016 election, Comey said: "I don't remember spelling it out, but it had to have been".
Comey also discussed the first time he met the newly elected Trump in person in January 2017 to talk about the allegations of Russian meddling in the 2016 US election. He strikes me as a person of above average intelligence who's tracking conversations and knows what's going on. So I was now as far away as physically possible, without going out the window, from the president.
Instead, Mr. Comey called Mr. Trump "morally unfit".
Asked if the president wanted the Justice Department to investigate Comey, White House spokeswoman Sarah Huckabee Sanders said Sunday on ABC's "This Week" that she was not aware of a specific request.
Later in the day, Comey wrote on Twitter that his book, "A Higher Loyalty", is about "ethical leadership".
Trump's legal fate may depend on whether he succeeds in undermining the credibility of Comey and the law enforcement institutions he views as arrayed against him. Just another of his many lies. The firing ultimately led to the appointment of Robert Mueller to direct a special counsel inquiry into Russian meddling in the 2016 USA presidential election and potential collusion between the Trump campaign and the Kremlin.
'I hope not because I think impeaching and removing Donald Trump from office would let the American people off the hook and have something happen indirectly that I believe they're duty bound to do directly, ' Comey said. "And so I was anxious about the organization, anxious about the people". But he said Trump's moral qualifications were lacking.
'People in this country need to stand up and go to the voting booth and vote their values'.
Trump finally saw Comey and called him forward, a walk which Comey described as feeling "like a thousand yards".
The president lashed out at Comey in a series of tweets earlier Sunday, saying that the email probe was handled "stupidly" and calling Comey a "slime ball". It raises the possibility that the Russians had filmed Trump enaged in unsavoury behaviour and could use the recording to blackmail him. 'And then he said, "Another reason you know it's not true is I'm a germaphobe".
Hours before the interview aired, Trump launched into a preemptive tirade on Twitter berating Trump.
Last year, a friend of Comey's told The New York Times that the Federal Bureau of Investigation director tried to use his long arms to initiate a hand shake, rather than a hug, as he finished crossing the room.
"I knew this was a no-win situation, this case". "His "memos" are self serving and FAKE!"