A sitting U.S. congressman took to social media Tuesday evening to issue a jeering — and possibly threatening — statement directed at former Trump lawyer Michael Cohen, who is due to testify publicly before the House Oversight Committee on Wednesday.

“Hey @MichaelCohen212,” Rep. Matt Gaetz, a Republican from Florida, wrote on Twitter. “Do your wife & father-in-law know about your girlfriends? 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…”

Gaetz, a staunch supporter of President Donald Trump, is not on the House Oversight Committee, but nonetheless his tweet sparked an immediate backlash, with critics expressing disbelief that he would taunt or threaten a witness who's about to testify, and a law blog suggesting he might have violated the law.

In a statement to VICE News, Lanny J. Davis, an attorney for Michael Cohen, said his client would "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."

Cohen previously postponed his congressional testimony, originally slated for Feb. 7, due to numerous threats against him and his family. "Due to ongoing threats against his family from President Trump and [Trump's lawyer] Mr. Giuliani, as recently as this weekend, as well as Mr. Cohen's continued cooperation with ongoing investigations, by advice of counsel, Mr. Cohen's appearance will be postponed to a later date," Davis said in a statement on Jan. 23.

Cohen, who will start a three-year prison sentence for tax evasion in May, and has already been convicted for lying to Congress once, is expected to spill the beans on his former employer Donald Trump in a big way.

Reports published Tuesday citing sources familiar with the matter suggested that Cohen may accuse Trump of crimes, and also discuss moments where the president lied or used racist language.

Former Director of United States Office of Government Ethics Walter Shaub replied to Gaetz’s tweet with a link to the federal witness tampering statute.

But Gaetz shrugged off any suggestion that he was “witness tampering.” “I’m witness testing,” he told Vox’s Alex Ward. “We are still allowed to test the veracity and character of witnesses, I think.”

This isn't the first time Cohen has face veiled or explicit threats from Trump and his backers. Trump and his lawyer Rudy Giuliani have both made statements about Cohen’s family that could be seen as witness tampering, former prosecutors have told VICE News.