A US senator has released a transcript of the testimony to Congress by the founder of the firm that researched Donald Trump’s alleged ties to Russia.
Glenn Simpson’s Fusion GPS produced a dossier purporting to show financial and personal links between President Trump, his advisers and Moscow.
It was compiled by former British spy Christopher Steele.
The White House and Republican lawmakers have questioned the firm’s credibility.
Senator Dianne Feinstein, a Democrat, said she had taken the step because of the “innuendo and misinformation” circulating about Fusion GPS, which were “part of a deeply troubling effort to undermine the investigation into potential collusion and obstruction of justice”.
“The only way to set the record straight is to make the transcript public,” she said in a statement.
Mr Simpson had requested the transcript of his 10 hours of testimony before the Senate Judiciary Committee be made public, the California congresswoman added.
Friday saw the committee’s Republican chairman, Charles Grassley, call for a criminal investigation into Mr Steele.