Adam Schiff, the committee's top Democrat, said in a statement yesterday that Mr Trump's Twitter comment stopped short of denying that the White House had tapes or recordings, and said the White House must respond in writing.
Comey's firing, however, has reportedly led to Mueller investigating Trump over whether he obstructed justice.
Trump suggested that his threat of tapes may have intimidated Comey into being more honest in his recollection of events.
Mr Comey, asked if there were recordings of their conversations, earlier this month said: "Lordy, I hope there are tapes".
Asked on Fox News whether Mr Mueller should step down, Mr Trump said: "We're going to have to see".
"You can't give the other side any opportunity to accuse you of political partisanship, which is why I think it was a mistake for Mueller to hire, essentially, people who have been large contributors to the [Clinton] campaign", said Dershowitz. Spicer noted that Comey "had been honest and told the president on three separate occasions that he wasn't under investigation".
Independents went for Comey over Trump, 47 to 17 percent.
Terrorist suspect shot dead after failed bombing in Brussels
The incident led to large crowds of "people running in every direction", according to one witness who contacted broadcaster RTL. Answering the journalists' questions, the spokesman said that the perpetrator "wanted to cause significantly more damage".
The president closed on a more positive note, saying, "Robert Mueller's an honorable man, and hopefully he'll come up with an honorable solution".
And in a Twitter boast, he said, "I've helped pass and signed 38 Legislative bills, mostly with no Democratic s upport, and gotten rid of massive amounts of regulations".
Praised by Earhardt for what she dubbed a "smart" move, the president retorted, "Well, it wasn't very stupid, I can tell you that".
"Trump changed the arc of his presidency on Day 110 by bouncing Comey".
Trump has gone on the record in tweets and in interviews, saying he fired Comey over the FBI's Russian Federation investigation.
Trump's disclosure that there are, in fact, no tapes weakens his credibility in the eyes of investigators probing ties between his associates and Russian Federation and also may expose him to fresh legal jeopardy.
In his testimony before the Senate Intelligence Committee, Comey described Trump allegedly asking for the director's loyalty during a private dinner on January 27.
After the tweet, Mr Comey testified before the Senate Intelligence Committee to make his account of interactions with the President public. "The whole thing is ridiculous, if you want to know the truth, from that standpoint".
When pressed, the White House pointed to a series of media reports suggesting that Trump's associateds were under surveillance from the intelligence community and former House Intelligence Chair Devin Nunes claimed that either the president or his associates were identified in NSA transcripts of conversations among foreign nationals.