During more than two hours of testimony, Comey told the Senate Intelligence Committee he believed Trump had directed him in February to drop an FBI probe into the Republican president's former national security adviser Michael Flynn as part of the broader Russian Federation investigation.
US President Donald Trump says he is "100%" willing to speak under oath about his conversations with ex-FBI chief James Comey.
"I don't understand why the president just doesn't clear this matter up once and for all", said Senator Susan Collins, a member of that committee, referring to the existence of any recordings.
Donald Trump and his team already seemed prepared to moving towards a contest of credibility with former FBI DirectorJames Comey, but at a White House press conference this afternoon, the president took the dispute to a whole new level.
"The American people deserve to hear directly from this president, under oath, about his charges with respect to Mr. Comey", said Sen Jack Reed, D-R.I.
'I'll tell you about that maybe sometime in the very near future, ' he said.
The former Federal Bureau of Investigation director accused the President of telling "lies, plain and simple" after he was sacked from the intelligence service last month.
He further denied ever asking Comey for his "loyalty", contradicting Comey's detailed allegations in his sworn testimony.
"Despite so many false statements and lies, total and complete vindication", Mr Trump wrote on Twitter, suggesting that Mr Comey, who was under oath at the hearing, had committed perjury.
Speaking to reporters a day after Mr Comey testified to the Senate intelligence panel, House Democratic leader Nancy Pelosi said it was "beyond the pale" that Mr Trump had asked Mr Comey, then head of the independent law enforcement agency, for his loyalty.
"Lordy, I hope there are tapes", Comey testified, The Hill reported. Comey did say he believed that his unwillingness to lift what Trump called the "cloud" of the Russian investigation hindering his ability to govern as another factor in his abrupt termination.
Comey would not say whether he thought Trump tried to obstruct justice, leaving that determination to Mueller.
In the Rose Garden Friday, the president was asked whether such tapes existed.
Mr Trump on Sunday accused Mr Comey of "cowardly" leaks and predicted many more from him.