Washington, April 16 Former FBI Director James Comey, in his first interview since being fired last May, said that Donald Trump is "morally unfit" to be US President, a "serial liar" who treated women like "meat" and it was "possible" that Russians had material that could be used to blackmail him.
In an exclusive interview with ABC News' chief anchor George Stephanopoulos on Sunday night, he also described him as a "stain" on everyone who worked for him.
The former head of the Federal Bureau of Investigation compared the Trump administration to a "mafia family" and said that the President was incinerating the country's crucial norms and traditions like a "wildfire".
Comey's remarks were the latest salvo in a war of words with the US President, who blasted the former FBI director on Twitter earlier. "Slippery James Comey, a man who always ends up badly, will go down as the WORST FBI Director in history, by far!" Trump wrote on Sunday.
The FBI chief was fired while the agency was probing possible collusion between Trump's 2016 presidential campaign and Russia's meddling in the US election. Comey is now a crucial witness for Special Counsel Robert Mueller's investigation into the Russia probe. Mueller is also a former FBI chief.
Comey however dismissed claims that Trump was medically unfit to hold office. "I don't buy this stuff about him being mentally incompetent or early stages of dementia... I think he's morally unfit to be President."
"A person who treats women like they're pieces of meat, who lies constantly... and insists the American people believe it, that person's not fit to be President of the US, on moral grounds," he added.
The interview came ahead of the release of his tell-all book "A Higher Loyalty: Truth, Lies, and Leadership" on Tuesday.
Also a lawyer, Comey made an allegation that Trump had cavorted with prostitutes in Moscow that left him vulnerable to blackmail by the Russian government.
"I think it's possible, I don't know... These are more words I never thought I'd utter about a President of the US, but it's possible."
Comey said that he would not favour impeaching Trump, because that "would let the American people off the hook" and the public was "duty bound" to vote Trump out of office in the next election.
The former FBI chief also took aim at Trump's personal appearance, saying his hands are "average-sized" and his skin is "orange".
"He had impressively coiffed hair, his tie was too long as it always is, he looked slightly orange up close with small white half-moons under his eyes, which I assume are from tanning goggles," he said.
During the interview, Comey repeated his assertion, made at a Congressional hearing that Trump told him that he expected loyalty and pressured him to drop an investigation into Michael Flynn. The former National Security Adviser has since pleaded guilty to lying to the FBI and is now cooperating with Muller.
Asked, "was President Trump obstructing justice?" Comey responded, "Possibly. It's certainly some evidence of obstruction of justice." Trump had denied asking Comey to stop investigating Flynn.
Comey said he had "grave" misgivings about the Trump presidency even before it began. In a meeting with then President Barack Obama in the last days of his administration, Comey said he told him: "I dread the next four years. But in many ways, I feel great pressure to stay to try and protect the institution I lead."
Comey also told ABC News that he knew the investigation into former Secretary of State Hillary Clinton's use of a private email server was going to present a "no-win situation" for him.
After the interview aired, Trump's party -- via the Republican National Committee -- said Comey's publicity tour for his new book showed "his true higher loyalty is to himself".