Stephanopoulos asks Comey if he believes the Russians have "something" on Trump, to which Comey responds, "I think it's possible".
Comey told ABC News that the title of the book came from that "bizarre conversation" he had with Trump at the White House in January 2017, shortly after his inauguration.
In the book, A Higher Loyalty:Truth Lies and Leadership, he also defended the timing of the book's publication in the midst of the ongoing Russian Federation inquiry and before the release of a Justice Department inspector general's examination into the FBI's handling of the Clinton email investigation, which Comey oversaw.
However, during the Senate hearing in May, Grassley asked if Comey had ever been an anonymous source or authorized someone else to do the same, not if Comey knew anyone else who had been an anonymous source, as Trump argued. It would be something that ... is higher than all the normal fights about policy.
Mueller is investigating Russian interference in the 2016 election and any potential ties between Trump campaign associates and Russia. Trump has denied any collusion. "Is Donald Trump unfit to be president?"
Barbara Bush, 92, to focus on 'comfort care'
Jenna Bush Hager , an anchor on NBC's Today show , told the programme that Mrs Bush is resting comfortably with family. Bush, who is at home in Houston, is one of only two first ladies who was also the mother of a president.
"I think it's possible".
"I would. I would", Comey replied.
Yet Comey said he hopes Trump will not be impeached and removed from office.
"This guy swung an election", Conway said on ABC's Good Morning America, seeming to suggest that Comey had contributed to Trump's victory - a theory unlikely to find favor with the president.
Her comments came the morning after Comey, in his first televised interview since being fired a year ago, said that he believed Trump was "morally unfit" to be president and recounted several meetings with the him, including one in which Comey says Trump asked for his loyalty.
Dak Prescott: Dez Bryant release was 'not my decision'
The only question was whether he'd be taking less than $12.5 million in 2018 salary with the Cowboys or with someone else. By cutting Bryant now, the Cowboys made a move to better themselves now, and free themselves financially moving forward.
"Values matter", Comey said. "Impeachment, in a way, would short-circuit that".
Trump also tweeted: "The big questions in Comey's badly reviewed book aren't answered like, how come he gave up Classified Information (jail), why did he lie to Congress (jail), why did the DNC refuse to give Server to the Federal Bureau of Investigation (why didn't they TAKE it), why the phony memos, McCabe's $700,000 & more?". He also says he made a conscious effort to check the president's hand size, saying it was "smaller than mine but did not seem unusually so". Lindsey Graham (R- S.C.) and Chuck Grassley (R-Iowa) who found transcripts in August showing that Comey had drafted a statement rejecting charges be filed against Clinton, about two months before Clinton ever spoke with FBI investigators. Asked whether Comey was a man of integrity, the Republican speaker said: "As far as I know", but added that he did not know him well.
Reuters and other news outlets have obtained copies of Comey's book before its formal release.
"A Higher Loyalty" won't be formally released until Tuesday, but explosive details have already spilled out into the media.
France persuaded Trump to strike in Syria, says Macron
France's participation in the US-led military operation in Syria sparked fierce debate at home on Saturday. The Western states have accused forces of Assad of an attack with the use of chemical weapons in Duma.
"This is nothing more than a poorly executed PR stunt by Comey to desperately rehabilitate his tattered reputation and enrich his own bank account by peddling a book that belongs in the bargain bin of the fiction section", she said. "He lied to Congress", White House press secretary Sarah Sanders said Sunday on ABC's "This Week".