Mr Trump fired Mr Comey in May 2017, as Mr Comey was leading an investigation into Russian meddling in the presidential election of 2016, which has now expanded to include investigations into possible collusion between Trump campaign officials and Russia. Mr Trump has repeatedly hit out at Mr Comey, in a series of tweets since experts of the book started to appear on Thursday, the president has called him a "slimeball" and a "liar".
In his first interview since being fired, Mr Comey painted a scything picture of the president.
“Our president must embody respect, and adhere to the values that are at the core of this country. The most important being truth. This president is not able to do that. He is morally unfit to be president,” he said.
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The wide-ranging television interview with ABC lasted for five hours, with a condensed one hour version being broadcast on Sunday night. Questions centred around the new book, which challenges the president’s character in labelling him a mafia don and raises doubts about his commitment to serving America. In the transcript of the interview Mr Comey said Mr Trump will “stain” everyone around him.
Mr Comey is clearly trying to set up a dichotomy between himself and the president, but there were few absolutely new revelations in the interview. Still that does not diminish the powerful spectacle of the former FBI director - who was involved in a number of major events in Mr Trump’s run for, and then first year in, the White House - denigrating the sitting president.
Having started as the one in charge of the FBI investigation into Russian election meddling, which included investigating any possible collusion between Trump campaign personnel and Moscow, Mr Comey had plenty to say on that subject.
Mr Comey said he thinks it is “possible” that President Donald Trump might be compromised by the Russians. He said it struck him as unlikely but he could not say it with “high confidence” like he could with other presidents he has worked.
“It is stunning, and I wish I wasn’t saying it, but it’s the truth,” Mr Comey said.
He also described the “weird” Trump Tower meeting in which after the election he briefed the president-elect on the contents of an unverified intelligence document compiled by former British spy Christopher Steele, including allegations that Mr Trump had been in a Moscow hotel room in 2013 with urinating Russian prostitutes.
“I did not go into the business about people peeing on each other” in his briefing with Trump, Comey said. “I just wanted to get it done and get out of there.”
Mr Trump has denied all allegations around the dossier.
As Mr Comey also described the two famous episodes of being alone with Mr Trump, one a dinner where Mr Comey said that Trump “I expect loyalty, I need loyalty.” and the other in the Oval Office when Mr Trump asked him “I hope you can let it go”, which Mr Comey took as a “direction” to drop an FBI investigation into Mr Trump’s former National Security Adviser Michael Flynn.
Mr Trump and the White House have denied wither conversation taking place, while Mr Flynn later pleaded guilty to lying to the FBI.
Asked whether he believed Mr Trump had committed obstruction of justice, Mr Comey said “it’s possible” and there was “ certainly some evidence” that it may have happened. Mr Trump has denied collusion with Russia and allegations of obstruction of justice.
Mr Comey has come under attack from Mr Trump in recent days in a number of tweets that have labelled him “slippery” and a “slimeball”. It is something he has in common with the man that took over the FBI Russia investigation, Special Counsel Robert Mueller, with Mr Trump having labelled that investigation a “witch hunt”.
The former FBI director said that if Mr Trump were to fire Mr Mueller, both Democrats and Republicans would have to recognise as Mr Trump’s “most serious attack yet on the rule of law.”
While there were a couple of lighter moments, including Mr Comey saying that when meeting Mr Trump for the first time he realised he had “impressively coifed hair” that “looks to be all his”.
“I stared at it pretty closely”, Mr Comey said, “and my reaction was, 'It must take a heck of a lot of time in the morning, but it's impressively coifed.’”
Mr Comey said that his role in the 2016 election, in re-opening and than closing an FBI investigation into the emails of Mr Trump’s rival candidate Hillary Clinton close to polling day “sucked”. Ms Clinton and some Democrats blame him for her loss, but Mr Comey said it was a “no-win” situation and that he was a “flawed human” trying to make decisions based on “higher values”.
Agencies contributed to this report