A top ally of President Trump appeared to threaten a witness on the eve of a high-profile congressional hearing, suggesting Tuesday that he would expose the president’s former lawyer Michael Cohen as a womanizer should he testify against Trump.

“Hey @MichaelCohen212 — Do your wife & father-in-law know about your girlfriends?” Rep. Matt Gaetz (R-Fla.), a fierce defender of the president, wrote on Twitter. “Maybe tonight would be a good time for that chat. I wonder if she’ll remain faithful when you’re in prison. She’s about to learn a lot.”

The comment elicited instant pushback from House Democrats, who accused Gaetz of trying to intimidate their star witness.

Cohen, Trump’s former fixer and longtime associate, is set to testify publicly before the House Oversight and Reform Committee on Wednesday. He will accuse the president of “lies, racism and cheating,” according to a person familiar with the matter who spoke on the condition of anonymity because they were not authorized to describe the expected testimony. And Cohen is expected to detail Trump’s role in his hush-money payments to two women alleging sexual relationships with Trump during the 2016 election.

The White House and Trump’s Capitol Hill allies have been trying to discredit Cohen before he captures the attention of the nation Wednesday, casting him as a liar who cannot be trusted. In a statement Tuesday, for example, White House press secretary Sarah Sanders called Cohen a “disgraced felon” and said “it’s laughable that anyone would take a convicted liar like Cohen at his word.”

Cohen pleaded guilty to multiple crimes last year, including lying to Congress about a Trump Organization project in Moscow and orchestrating hush-money payments to women who claimed during the 2016 election to have had sexual encounters with the president. He has said he is finished with lying and is seeking to tell his story.

Reached by phone Tuesday evening, Gaetz said the tweet “speaks for itself.” He would not say whether Republicans on the oversight committee intended to use this allegation during Wednesday’s hearing; Gaetz is not a member of the committee, but he is close with Republicans who are, including ranking member Jim Jordan (R-Ohio). 

Gaetz gave no proof or details about what he meant in his tweet. Asked whether his actions constituted witness intimidation, he balked: “Challenging the credibility and veracity of a witness is something that happens every day in America, and we need more of that in Congress when people intend to come and lie to us.”

Lanny J. Davis, an attorney for Cohen, said in a statement to The Washington Post: “We will not respond to Mr. Gaetz’s despicable lies and personal smears, except to say we trust that his colleagues in the House, both Republicans and Democrats, will repudiate his words and his conduct.

“I also trust that his constituents will not appreciate that their congressman has set a new low — which in today’s political culture is hard to imagine as possible.”

Criticism of Gaetz’s comment, meanwhile, lit up the twittersphere. Former GOP representative David Jolly (R-Fla.) tweeted that Gaetz’s message was “a new low in an age of low, and possibly a crime by a sitting Congressman.” Rep. David N. Cicilline (D-R.I.) said on Twitter: “This isn’t a scene from Godfather II. Witness intimidation is not going to work. The truth will come out.”

Sen. Christopher A. Coons (D-Del.) said on CNN that Gaetz’s tweet constituted a lawmaker “badgering a witness . . . badgering of the type that seems more like it’s out of a mob novel or a TV show.” Asked whether there should be consequences, he said he would leave it up to the House oversight committee. But Gaetz’s behavior, he continued, “lies well outside the boundaries of typical conduct here.” If it were in a legal case, it would “arguably constitute witness intimidation,” he said.

“I keep being shocked, and I keep thinking there is nothing that will shock me more . . . this tweet you’ve just put up on television is really something,” Coons said.

Rep. Bill Pascrell Jr. (D-N.J.) called for the House Ethics Committee to investigate Gaetz’s comments.

“One of my colleagues, a duly elected member of Congress, has taken to Twitter to intimidate a witness,” he tweeted. “This is grossly unethical and probably illegal. House Ethics must investigate this disgrace and stain on our institution.”

House Speaker Nancy Pelosi (D-Calif.) stopped short of explicitly calling for an investigation into Gaetz’s actions. But in a Tuesday-night statement, she gave him a stern warning.

“I encourage all members to be mindful that comments made on social media or in the press can adversely affect the ability of House committees to obtain the truthful and complete information necessary to fulfill their duties,” she said. “As a result, such statements can be construed as not reflecting credibility on the House, and the Committee on Ethics should vigilantly monitor these types of statements, which may not be protected by the speech or debate clause.”

House Democrats have accused the president of trying to intimidate Cohen by suggesting in early January that Cohen’s father-in-law had legal exposure as soon as he agreed to appear before the panel. Trump even called Cohen a “rat,” moblike language that Democrats say contributed to Cohen’s concern for his and his family’s safety. 

Democrats also called it proof that Trump, who is overseas meeting with the leader of North Korea this week, is terrified of what secrets Cohen might reveal.

“Hard to combine disgusting and maybe criminal stupidity in one tweet but, hey, you did it. Keep this up, Cohen’s going to need a double cell,” said Rep. Sean Maloney (D-N.Y.).

Trump has said publicly he is not concerned about Cohen’s testimony, but privately, his advisers said they are preparing for the president’s former personal attorney to delve into a number of issues that would be uncomfortable for Trump, including his hush-money payments to women.

White House officials have expressed frustration about the split-screen spectacle expected Wednesday, when Cohen’s testimony is scheduled to begin just after Trump finishes dinner in Hanoi with North Korean leader Kim Jong Un, as the leaders meet for high-stakes nuclear arms negotiations. 

“It’s unfortunate this is happening now,” said one White House official, who spoke on the condition of anonymity to discuss the Cohen hearing.

Philip Rucker in Hanoi and Matt Zapotosky in Washington contributed to this report.