A House Republican taunted US President Donald Trump's former lawyer Michael Cohen before a congressional hearing, suggesting that the public appearance would expose damaging personal information about him.
Florida representative Matt Gaetz tweeted on Tuesday that the world is “about to learn a lot” about Cohen and that he should talk to his wife before his testimony on Wednesday.
Mr Gaetz, a Trump ally, is not a member of the committee questioning Cohen.
But the tweet was extraordinary because his remarks appeared to be threatening or intimidating a witness on the eve of a highly anticipated public hearing.
Cohen is due to testify before the House oversight and reform committee about payments to buy the silence of women who said they had affairs with Mr Trump before the 2016 election.
His testimony is expected to be sharply critical of the president, claiming lies, cheating and criminal behaviour.
“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,” said Cohen’s lawyer, Lanny Davis.
Asked whether his tweet should be perceived as a threat, Mr Gaetz responded: “Absolutely not”.
“We’re witness testing, not witness tampering, and when witnesses come before Congress their truthfulness and veracity are in question, and we have the opportunity to test them,” he said.
A spokesman for House Minority Leader Kevin McCarthy did not immediately respond to a request for comment.
Mr Trump’s former fixer was testifying to the Senate intelligence committee behind closed doors on Tuesday when Mr Gaetz tweeted, alleging Cohen was guilty of infidelities but offering no evidence.
It was not clear what prompted the allegation, but Mr Gaetz’s tweet drew immediate criticism from fellow politicians.
Democrat Bill Pascrell Jr called on the House ethics committee to launch an investigation for what he called a “grossly unethical and probably illegal” attempt to intimidate a witness.
Speaker Nancy Pelosi in a tweet on Tuesday evening urged the ethics committee to “vigilantly monitor comments made on social media or in the press that can adversely affect the ability of House committees to obtain the truthful and complete information necessary to fulfil their duties".
Cohen had previously delayed his public testimony, blaming threats from Mr Trump and his lawyer and spokesman, Rudy Giuliani.
He also gave his continuing co-operation in special counsel Robert Mueller’s Russia investigation as a reason.
Cohen, who was a key power player in The Trump Organisation for more than a decade and a fixture in Mr Trump’s political life, is a central figure in the Mueller investigation into possible co-ordination between Russia and the president’s campaign.
He played a pivotal role in buying the silence of adult film actress Stormy Daniels and former Playboy Playmate Karen McDougal, who both claimed they had affairs with Mr Trump. The president has denied their claims.
Cohen has pleaded guilty to campaign finance offences connected to the payments and lying to Congress. Federal prosecutors have said Mr Trump directed Cohen to make the payments during the campaign.
Cohen is scheduled to begin a three-year prison sentence in May.