Ohio Representative Jim Jordan spent most of Wednesday’s impeachment hearings criticizing the witnesses who testified, the Democratic lawmakers who called them, and the inquiry itself. He also reiterated a common demand among President Donald Trump’s allies: bring forward the anonymous civil servant whose complaint helped surface the Ukraine scandal. “There is one witness that they won’t bring in front of us, they won’t bring in front of the American people,” Jordan said, referring to House Democrats. “That’s the guy who started it all: the whistleblower.”

After Jordan yielded his time, Vermont Representative Peter Welch gave a barbed retort before turning to his own questions for the witnesses. “I’d be glad to have the person who started it all,” he told the Ohio Republican from across the committee hearing room. “President Trump is welcome to come in and sit down right there.” The jab elicited a murmur of laughter throughout the audience and plaudits from Trump’s critics on social media.

Whether intentionally or not, Welch raised a good point. Trump has vociferously asserted that he didn’t do anything wrong in his July 25 conversation with Ukrainian President Volodymyr Zelenskiy. He regularly insists that the phone call was “beautiful” and “perfect,” and that he’s being framed by vindictive Democrats who are trying to mount a coup against him. If the president feels that strongly about it, the House of Representatives should give him the opportunity to make his case in person before lawmakers and the American public.

It would be extraordinary for a president to testify before Congress on any matter, let alone his own impeachment. But it’s not without precedent. Three sitting presidents have testified in some way before lawmakers over the past 230 years, according to the Senate Historical Office. In 1789, George Washington appeared before the entire Senate alongside his secretary of war to discuss a treaty with Indian tribes; senators eventually voted to get his answers in writing instead. Abraham Lincoln also quietly testified before the House Judiciary Committee in 1862 to discuss who had leaked part of his State of the Union message to a newspaper before he sent it to Congress. He assured lawmakers that no one in his family was responsible.

The third and most relevant instance took place 112 years later. One month after he took office in 1974, Gerald Ford shocked the country by granting a full pardon to his predecessor Richard Nixon for any crimes committed during the Watergate crisis. In a televised address, Ford said that Nixon and his family had “suffered enough” during the national ordeal, and that he wanted to provide a sense of closure to the scandal. “My conscience tells me it is my duty, not merely to proclaim domestic tranquility but to use every means that I have to insure it,” he said. “I do believe that the buck stops here, that I cannot rely upon public opinion polls to tell me what is right.”