Glenn Simpson, founder of the research firm Democrats hired to dig into President Trump during the 2016 race, told congressional investigators that the author of a controversial Trump dossier believed the candidate "was being blackmailed" and urged the firm to contact the FBI, according to a transcript released on Tuesday.

Hillary Clinton and the Democratic National Committee hired Fusion GPS, Simpson's firm, to research Trump in 2016. Fusion GPS in turn hired Christopher Steele, a former top British intelligence officer, to dig into Trump's business dealings in Russia.

Sen. Dianne Feinstein, D-Calif., released the transcript of Simpson's August 2017 interview with the Senate Judiciary Committee amid tensions with committee Republicans over whether the transcript should be made public.

Simpson's testimony about Steele's blackmail fears came during a discussion of the cyberattack that hit the DNC in July 2016, at which time Russian-linked hackers stole thousands of emails from Democrats and published them through WikiLeaks. They began to wonder, as Steele compiled more information about Trump's alleged Russia ties, whether they should take their research to the FBI.

"Chris said he was very concerned about whether this represented a national security threat and said he wanted to — he said he thought we were obligated to tell someone in government, in our government about this information," Simpson said. "He thought from his perspective there was an issue — a security issue about whether a presidential candidate was being blackmailed. From my perspective, there was a law enforcement issue about whether there was an illegal conspiracy to violate the campaign laws, and then somewhere in this time the whole issue of hacking has also surfaced."

Simpson said he hesitated to take the dossier to the FBI, in part because he did not have any contacts in the bureau to whom he could bring his research. Steele pushed to bring the dossier to the government, Simpson said.

"I don't remember the exact sequence of these events, but my recollection is that I questioned how we would do that because I don't know anyone there that I could report something like this to and be believed, and I didn't really think it was necessarily appropriate for me to do that," Simpson said. "In any event, he said, 'Don't worry about that, I know the perfect person, I have a contact there, they'll listen to me, they know who I am, I'll take care of it.' I said, 'Okay.' You know, I agreed, it's potentially a crime in progress. So, you know, if we can do that in the most appropriate way, I said it was okay for him to do that."

Republicans have accused the Obama administration's Justice Department of using the Steele dossier to open a criminal investigation into the Trump campaign without first corroborating the research Democrats paid to compile. Democrats have said other allegations of criminal activity must have tipped the FBI to possible collusion between Trump associates and Russians looking to sway the election.

Simpson told congressional investigators that Steele wanted to go to the FBI out of fear that the Russians had obtained damaging information about Trump. That part of the dossier has not been confirmed publicly by investigators or reporters.

"His concern, which is something that counterintelligence people deal with a lot, is whether or not there was blackmail going on, whether a political candidate was being blackmailed or had been compromised," Simpson said. "And the whole problem of compromise of western businessmen and politicians by the Russians is an essential part of — it's like disinformation, it's something they worry about a lot and deal with a lot and are trained to respond to. So, you know, a trained intelligence officer can spot disinformation that you or I might not recognize, certainly that was Chris's skill, and he honed in on this issue of blackmail as being a significant national security issue. Chris is the professional and I'm not. So I didn't agree with that — it wasn't that I disagreed with it. It was that I didn't feel qualified to be the arbitrar of whether this is a national security expert. He's the pro and I'm the ex-journalist."