FBI Director James Comey testifies before the Senate Judiciary Committee at the U.S. Capitol in Washington, United States on May 3, 2017. Samuel Corum | Anadolu Agency | Getty Images

Former FBI Director , who was fired by President Donald Trump, gave his first media interview since the dismissal in an ABC "20/20" interview that aired Sunday night. The interview came shortly before Comey's book, "A Higher Loyalty," was set to be released on Tuesday. The memoir details the fired FBI chief's personal experiences with Trump, and spends ample time criticizing Trump's behavior in the White House and his relationship to the truth. In an exclusive interview with ABC News Chief Anchor George Stephanopoulos, Comey gave his first on-camera remarks since being fired by Trump in May 2017. Here are the most revealing things he said:

Comey said Trump's alleged request about former national security advisor Michael Flynn was 'certainly some evidence of obstruction of justice'

In the interview, Comey recounted his February 2017 conversation with Trump in the Oval Office regarding ex-top advisor Michael Flynn. Comey said that Trump's words, and the circumstances surround the meeting, provided "evidence of obstruction of justice" by the president. The White House said Flynn was fired for misleading Vice President Mike Pence about his communications with Russian ambassador Sergey Kislyak. When Trump brought up Flynn in the one-on-one conversation, Comey said the president told him, "I hope you can let it go," referring to an investigation into Flynn by the FBI at the time. Asked in the ABC interview whether he believed Trump was obstructing justice in making the request, Comey said: "Possibly. I mean, it's certainly some evidence of obstruction of justice." "It would depend and – and I'm just a witness in this case, not the investigator or prosecutor, it would depend upon other things that reflected on his intent," he added. Comey also rhetorically asked why Trump asked other top advisors to leave the room if he "didn't know he was doing something improper." "Why did he kick out the attorney general and the vice president of the United States and the leaders of the intelligence community? I mean, why am I alone if he's – doesn't know the nature of the request?"

Comey said he thinks Trump is 'a person of above average intelligence,' but 'morally unfit to be president'

Pundits have often discussed the president's intelligence throughout his time in politics. Trump himself has weighed in, at one point describing himself as a "very stable genius." "I often hear people talk about it. I don't buy this stuff about him being mentally incompetent or early stages of dementia," Comey said in the Sunday interview. "He strikes me as a person of above average intelligence who's tracking conversations and knows what's going on. I don't think he's medically unfit to be president." Comey added: "I think he's morally unfit to be president."

Comey disputes criticism of his handling of Hillary Clinton's email scandal – from all ends of the political spectrum

In "What Happened" a post-mortem on her failed presidential candidacy in 2016, Hillary Clinton said she felt "shivved" by Comey for the way he handled her email scandal. Many Republicans have also been quick to criticize Comey – especially Trump, who accused Comey of "making decisions based on the fact that he thought she was going to win" as a quid pro quo for a position in her administration. Comey pushed back against all sides in the ABC interview. "It's illustration of our polarization here that you've got the Trump camp, which I guess thinks I was trying to save Hillary Clinton. They don't quite explain what I was doing in October," he said. "And then Clinton camp thinks I was trying to shiv Hillary Clinton. Both can't be true, but in our polarized world, people live in separate bubbles," Comey argued. "I would hope both camps will read this and, I hope, see a deeply flawed human surrounded by other flawed humans trying to make decisions with an eye, not on politics, but on those higher values."

Comey said 'it's possible' that salacious allegations from the controversial Fusion GPS dossier could be true

In his book, Comey recounts Trump's many vociferous denials of a scandalous rumor from a largely unverified dossier that surfaced after the 2016 election. In multiple interactions, according to the former FBI director, Trump told Comey that there was "no way" he would let prostitutes perform sex acts involving urine, as he was alleged to have done in Moscow in 2013, according to the now-infamous dossier. The claim in the dossier has not been verified. Comey said in his memoir that Trump denied the story to him on at least three separate occasions. "I honestly never thought this words would come out of my mouth, but I don't know whether the – the – current president of the United States was with prostitutes peeing on each other in Moscow in 2013. It's possible, but I don't know," Comey said in the television interview.

Comey said he regrets not pushing back harder against former Attorney General Loretta Lynch on the Clinton email scandal