WASHINGTON >> The founder of a firm that commissioned a dossier of allegations about President Donald Trump’s ties to Russia told congressional investigators that its author took it to the FBI because of a concern about “whether a political candidate was being blackmailed.”

California Sen. Dianne Feinstein, the top Democrat on the Senate Judiciary Committee, released a transcript today — over the objections of the committee’s Republican chairman, Iowa Sen. Chuck Grassley — from an August closed-door interview with Fusion GPS co-founder Glenn Simpson. Simpson’s firm commissioned the dossier, which was initially paid for by a conservative website tied to Republicans and then later by Democrats, including Democrat Hillary Clinton’s presidential campaign.

Simpson said Christopher Steele, the former British spy who wrote the dossier, took it to the FBI in July 2016, and said his concern was “whether or not there was blackmail going on, whether a political candidate was being blackmailed or had been compromised.”

Several GOP-led committees are now investigating whether the dossier formed the basis for the FBI’s initial investigations. Simpson has denied that it did, and, according to the transcript, told investigators that the FBI told Steele that the government had intelligence from “an internal Trump campaign source.” Simpson would not name the source.

The dossier is a compilation of memos written by Steele during the 2016 campaign that contained allegations of connections between Trump and Russia, including that Trump had been compromised by the Kremlin. Trump has derided the dossier as a politically motivated hit job.

Simpson told investigators it was his understanding that the FBI “believed Chris’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.” It’s unclear whether he was referring to Trump’s campaign or his business, which goes by the name the Trump Organization.

Citing the Republican attempt to discredit the dossier, Simpson has called for the release of multiple closed-door interviews he has done as part of congressional Russia investigations, including his interview with Judiciary. He has also talked to the House and Senate intelligence committees.

Democrats have charged that the FBI investigations are meant to be a distraction from separate investigations into the Russian meddling and whether Trump’s campaign was involved. They have also called for the release of the transcripts.

Feinstein said in a statement that Americans deserve to see what Simpson said.

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

In a statement, Fusion GPS said it “commends Sen. Feinstein for her courage. The transcript of Glenn Simpson’s lengthy responses to the Senate Judiciary Committee’s questioning speaks for itself.”

Grassley and Republican Sen. Lindsay Graham last week asked the Justice Department to investigate Steele, saying they had information about false statements he may have made to the government. Democrats criticized the move, saying they were targeting someone who had reported wrongdoing, not committed it.

Simpson told investigators that Steele is “basically a Boy Scout,” saying he has worked with Steele on and off since 2009 and he knew him to be “a person who delivered quality work in very appropriate ways.”

Associated Press writers Eric Tucker and Chad Day contributed to this report.