House Judiciary Committee Chairman Jerry Nadler (D-NY) on Monday subpoenaed former White House counsel Don McGahn for “testimony and documents” as part of the panel’s sweeping obstruction probe into President Donald Trump.

Nadler said in a statement that McGahn is a “critical witness” about whether Trump obstructed justice in incidents described in special counsel Robert Mueller’s report on now-debunked collusion between the 2016 Trump campaign and Russia.

“Mr. McGahn is a critical witness to many of the alleged instances of obstruction of justice and other misconduct described in the Mueller report,” the New York Democrat said. “His testimony will help shed further light on the president’s attacks on the rule of law, and his attempts to cover up those actions by lying to the American people and requesting others do the same. Nadler wants McGahm to appear before his panel next month.

Nadler has subpoenaed the Justice Department for the full, unredacted report and said Sunday he was adding McGahn to the list of people he would call to testify before his committee, along with Mueller and Attorney General William Barr.

And… the House Judiciary Committee just subpoenaed Don McGahn. pic.twitter.com/idJSxdvAo8 — Jennifer Bendery (@jbendery) April 22, 2019

The subpoena angered Republicans even as it functioned as a reassurance to impatient Democrats who have called for Trump’s impeachment.

Rep. Doug Collins (R-GA), the panel’s ranking Republican, said in a statement: “For the second time in four days, the chairman has issued a subpoena prematurely and contrary to his pledge not ‘to issue a subpoena every time we have a disagreement with the administration.’ Don McGahn sat for more than 30 hours of interviews with the special counsel’s investigation, and the chairman has answered that with a stunning 36-item subpoena. Instead of looking at material that Attorney General [William] Barr has already made available, Democrats prefer to demand additional materials they know are subject to constitutional and common-law privileges and cannot be produced.”

McGahn was a vital witness for Mueller, recounting the president’s outrage over the investigation and his efforts to curtail it.

He described, for instance, being called at home by the president on the night of June 17, 2017, and directed to call the Justice Department and say that Mueller had conflicts of interest and should be removed. McGahn declined the command, “deciding that he would resign rather than trigger what he regarded as a potential Saturday Night Massacre,” the Mueller report said.

Nadler’s announcement came as he joined Pelosi on a conference call with rank-and-file Democrats for the first caucus-wide discussion of the Mueller report since it was released on Thursday. In a letter earlier Monday, Pelosi acknowledged that the party’s officeholders have a range of views on how to proceed. But she counseled them repeatedly to go after facts, not resort to “passion or prejudice” in the intense run-up to the 2020 presidential and congressional elections.

“While our views range from proceeding to investigate the findings of the Mueller report or proceeding directly to impeachment, we all firmly agree that we should proceed down a path of finding the truth,” Pelosi wrote in a letter to Democrats. “It is also important to know that the facts regarding holding the President accountable can be gained outside of impeachment hearings.”

“As we proceed to uncover the truth and present additional needed reforms to protect our democracy, we must show the American people we are proceeding free from passion or prejudice, strictly on the presentation of fact,” she added.

The AP contributed to this report.