A day before the hearing, the committee voted to authorize Nadler to subpoena Whitaker after the acting attorney general decline to answer certain questions submitted in advance about communications with White House officials and Whitaker's refusal to recuse himself from supervising Mueller's investigation, contrary to the recommendation of the top Justice Department's ethics adviser.
Whitaker insisted Thursday that that was not the case, saying he had "devoted considerable resources and numerous hours to my preparation" and was looking forward to the hearing.
The exchange grew more contentious when Whitaker flatly refused to answer Nadler when he asked whether Whitaker's approval had ever been requested for action by Mueller's probe.
Nadler originally invited Whitaker to appear before the committee for an open hearing scheduled for Friday. He even quipped at Chairman Jerrold Nadler (D-NY) at one point that his "five minutes was up".
On Thursday evening, Nadler said no subpoena would be issued if Whitaker appeared before the committee Friday prepared to answer questions.
Nadler responded to the Justice Department letter by telling Whitaker that a subpoena would not be necessary if he answered lawmakers' questions, and questions he would not be able to answer would be handled on a "case-by-case basis". "That would have been considered a development that I would have been briefed on and I was briefed on that".
Whitaker also made clear he will not cooperate with the Committee.
Whitaker testified he had never spoken with members of Trump's inner circle about his views on the probe as a private citizen before he joined the Justice Department. "I'm here voluntarily, I agreed to five-minute rounds".
But after Collins raised the claim that CNN had been tipped off of the arrest by federal authorities, Whitaker said he did not "know of any other special counsel's office notice or DOJ notice to media outlets of Mr".
"If you appear before the committee tomorrow morning and you are prepared to respond to questions from our members, then I assure you that there will be no need for the committee to issue a subpoena on or before February 8", Nadler wrote in a letter to Whitaker. Jerry Nadler (D-N.Y.) questioned Whitaker about special counsel Robert Mueller's investigation into Russian interference in the 2016 election and allegations of collusion or obstruction of justice by the commander-in-chief.
At the hearing, Whitaker said that he had not interfered in the Mueller investigation. Whitaker was an outspoken critic of the investigation before arriving at the Justice Department in 2017. "In the current environment, the American people have to know that there are places in government where the rule of law-not politics-holds sway, and where they will be treated fairly based exclusively on the facts and an even-handed application of the law", he said during his testimony last month. It's not attorney general quality performance.
Nadler later agreed to drop the threat, after Whitaker said he would back out from testifying if the subpoena was served.
Republicans, who until recently led the committee, complained on Friday that the hearing was a "dog and pony" show meant to discredit the president.