White House counsel Don McGahn looks on as President Donald Trump speaks during a cabinet meeting in the Cabinet Room of the White House, Wednesday, Oct. 17, 2018, in Washington. Evan Vucci | AP

House Judiciary Committee Chairman Rep. Jerry Nadler of New York on Monday announced that he had issued a subpoena to former White House counsel Donald McGahn seeking testimony and documents related to the committee's investigation into potential obstruction of justice by President Donald Trump. The subpoena comes days after a partially redacted copy of special counsel Robert Mueller's report was released to the public. McGahn's testimony forms a crucial basis of the report's discussion of the president's attempts to end Mueller's 22-month probe, which ultimately proved unsuccessful. Mueller declined to determine whether the president's acts amounted to criminal obstruction. "Mr. McGahn is a critical witness to many of the alleged instances of obstruction of justice and other misconduct described in the Mueller report," Nadler said in a statement. "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."

The subpoena calls for McGahn to provide documents to the committee by May 7, and to testify May 21. The documents requested cover a wide range of topics, including those related to the June 2016 Trump Tower meeting between Trump campaign officials and a Russian lawyer, potential pardons for Trump associates and Mueller's alleged conflicts of interest. The demand for documents and testimony drew backlash from the committee's Republicans. "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.'" Rep. Doug Collins, the top Republican on the committee, said in a statement. "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," the Georgia Republican said. "Instead of looking at material that Attorney General 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." The subpoena comes as pressure mounts on Democrats to make a decision on impeachment. "Some of this would be impeachable," Nadler said Sunday on NBC's "Meet the Press," referring to the findings of Mueller's investigation. "Obstruction of justice, if proven, would be impeachable."