A U.S. Democratic senator on Tuesday released testimony from the founder of the Fusion GPS firm that during the 2016 presidential election campaign researched Donald Trump’s ties to Russia and produced a dossier that has been denounced by the White House.

The Washington research firm has been under attack by the White House and Republican lawmakers over the dossier, which is central to investigations in Congress and by a federal special counsel into allegations that Russia interfered in the election to help Trump win, and any potential collusion by the Trump campaign.

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“The innuendo and misinformation circulating about the transcript are part of a deeply troubling effort to undermine the investigation into potential collusion and obstruction of justice,” said Dianne Feinstein, who is the senior Democrat on the Senate Judiciary Committee.

“The only way to set the record straight is to make the transcript public,” she said in a statement.

Fusion GPS founder Glenn Simpson, who previously worked as a reporter at the Wall Street Journal, had asked that a transcript of his 10 hours of testimony in August before Judiciary Committee staff be made public, Feinstein said.

The congressional panel is one of three investigating the Russia matter. Russia has denied allegations of election meddling and Trump denies any collusion by his campaign with Moscow.

Feinstein released the testimony after the panel’s Republican chairman, Charles Grassley, called on Friday for a criminal investigation into former British spy Christopher Steele. Steele was working for Fusion GPS when he compiled a “dossier” of allegations of financial and personal links between Trump, his advisers and Russia.

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Although several news organizations, including Reuters, were briefed on Steele’s dossier before the November 2016 election, most decided not to report on the material because its inflammatory and sometimes salacious content could not be verified.

In the testimony, Simpson said the Steele dossier was taken seriously by the FBI because it corroborated reports the bureau had received from other sources.

Steele met with an FBI official in Rome to discuss his findings and reported back on their exchange, Simpson told the committee.

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“Essentially what he told me was they had other intelligence about this matter from an internal Trump campaign source,” Simpson said.

“My understanding was that they believed Chris at this point – that they believed Chris’s (Steele’s) information might be credible because they had other intelligence that indicated the same thing and one of those pieces of intelligence was a human source from inside the Trump organization,” Simpson said.

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‘BOGUS’ DOSSIER

Republicans have sought to attack the credibility of Special Counsel Robert Mueller’s investigation into Russian election meddling in part by raising concerns about the Steele dossier.

They have, for instance, questioned whether the FBI paid for it and also repeatedly sought to find out if it was used by U.S. law enforcement and intelligence agencies as the basis to obtain a surveillance warrant from the special Foreign Intelligence Surveillance Court, in order to spy on Trump associates during the campaign.

President Trump, for his part, has repeatedly slammed the dossier on Twitter and called it “bogus.”

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Grassley’s office slammed Feinstein for releasing the testimony, saying it came as the panel was still trying to secure testimony from other witnesses, including Trump’s son-in-law, Jared Kushner.

“Her action undermines the integrity of the committee’s oversight work and jeopardizes its ability to secure candid voluntary testimony,” said Grassley spokesman Taylor Foy.

“Fusion GPS commends Sen. Feinstein for her courage,” the research firm said in a statement.

Simpson and Fusion co-founder Peter Fritsch had urged the committee’s Republican leaders to release transcripts of their testimony in a New York Times opinion piece last Tuesday entitled “The Republicans’ Fake Investigations.”

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(Reporting by Sarah N. Lynch, Doina Chiacu, Mark Hosenball, and John Walcott; Editing by Susan Thomas and Frances Kerry)