WASHINGTON — Just days after a majority of House Democrats came out in favor of moving ahead with an impeachment inquiry into President Donald Trump, the House Judiciary Committee filed a lawsuit Wednesday to compel testimony from a central witness of the Mueller report.

The panel's move was an effort to enforce a subpoena to require former White House counsel Don McGahn — considered to be perhaps the most crucial witness in an obstruction of justice case against Trump which the Judiciary Committee has been investigating since earlier this year — to testify.

"McGahn, who was the White House Counsel during the relevant period, is the most important witness, other than the President, to the key events that are the focus of the Judiciary Committee’s investigation," the committee said in the filing, saying McGahn had “defied” the subpoena “at the direction of President Trump,” and asking the court to order him to comply.

Few names appear more often — more than 500 times in the redacted version of former special counsel Robert Mueller’s final report — than McGahn’s. The longtime Republican insider who served as both Trump’s campaign counsel and the first White House counsel sat for more than 30 hours of voluntary testimony before Mueller’s team.

“This represents another significant moment in the evolution of the committee’s investigation of whether or not to recommend articles of impeachment against President Trump,” Democratic counsel for the House Judiciary Committee told reporters of Wednesday’s filing, adding: “Don McGahn has the goods on Donald Trump.”

McGahn's attorney, William A. Burck, said in a statement that the former White House counsel had "an ethical obligation to protect client confidences," but that he "does not believe he witnessed any violation of law."

Burck added that the president had told McGahn "to cooperate fully with the Special Counsel but directed him not to testify to Congress unless the White House and the Committee reached an accommodation. When faced with competing demands from co-equal branches of government, Don will follow his former client’s instruction, absent a contrary decision from the federal judiciary."

McGahn is a key player in what Democrats believe is one of the clearest cases of obstruction of justice outlined in the report: Trump’s directive that he fire Mueller. Trump has disputed McGahn’s account to Mueller since the report was published, placing greater importance on what McGahn would testify to publicly under oath before Congress.

The White House ordered McGahn not to testify before the Judiciary Committee on May 21, which then resulted in the full House voting June 11 to allow the panel to go to court and enforce subpoenas to both McGahn and Attorney General William Barr.

When Mueller testified before the House Judiciary and Intelligence committees last month, he would not elaborate much on his 448-page report but did say it was "correct" that Trump asked McGahn to misrepresent facts he knew to be accurate to defend the president.

"So it's fair to say the president tried to protect himself by asking staff to falsify records relevant to an ongoing investigation?" Rep Cedric Richmond, D-La., asked then.

"I would say that's generally the summary," Mueller agreed.

Since Mueller’s testimony, more than two dozen additional Democrats have publicly voiced support for moving ahead with the impeachment process.

And on Friday, the 118th House Democrat called for opening an impeachment inquiry into Trump, despite Speaker Nancy Pelosi urging the caucus to focus their attention on congressional investigations and ongoing legal battles.

House Judiciary Chairman Jerry Nadler, D-N.Y., has publicly agreed with Pelosi’s approach and said his panel is investigating what, if anything, to recommend to the House regarding impeachment. This week, he gave a more detailed and aggressive timeline for making a recommendation than he had previously indicated.

Speaking on Morning Joe on Monday, Nadler said he would not let the election calendar dictate his committee’s work and indicated the possibility of recommending articles of impeachment for Trump by the late fall.

“I think we will probably get court decisions by the end of October, maybe shortly thereafter. We'll have hearings September and October with people who don’t … witnesses who are not dependent on the court proceedings. And we'll do it through the fall,” Nadler said, adding that “if we decide to report articles of impeachment, we could get it late in the fall, in the latter part of the year.”

The Judiciary Committee late last month also asked a federal court for the grand jury material from the former special counsel’s investigation. The court is not expected to rule on the Judiciary’s request for the grand jury material for at least two months.

The committee had reached an agreement with McGahn’s former chief of staff in the White House, Annie Donaldson, to provide written responses to questions as part of their obstruction of justice probe. But Democrats say that White House lawyers blocked her from doing so in 212 instances, according to a transcript, including whether she was present when Trump made certain directives, such as urging then-attorney general Jeff Sessions not to recuse himself from the Russia probe.

The panel has also already heard from former Trump White House aide Hope Hicks behind closed doors for nearly seven hours in June, but has requested she appear again after the committee said a federal judge in New York unsealed evidence that showed apparent inconsistencies in her testimony.