Three months ago, Special Counsel Robert Mueller completed his investigation into Russian election interference and President Donald Trump’s obstruction of justice. When the redacted report finally became available to Congress and the American people, it painted a damning picture of a corrupt president who welcomed and encouraged an attack on our country, capitalized on it, and then tried to cover up what he had done.

During his press conference announcing the end of his investigation, Mueller pointed out that the Department of Justice believes “the Constitution requires a process other than the criminal-justice system to formally accuse a sitting president of wrongdoing.” He was referring, without using the word, to impeachment—a process by which the U.S. House indicts, and the Senate convicts, a sitting president.

Congress has patiently tried to work within traditional means to get to the bottom of this extraordinary situation. Committees have called witnesses and requested evidence, only to be stonewalled by Trump and his associates. The president’s refusal to comply with the Constitution, statutes, and established congressional oversight defies the rule of law.

Mueller’s testimony before the House Judiciary and Intelligence Committees was a watershed moment. At this point, it is up to Congress to act on the evidence of multiple counts of obstruction of justice committed by the president, and to continue our investigation into whether he has committed other high crimes and misdemeanors.