In January, a dossier about Donald Trump’s possible Russia ties, prepared by former British intelligence officer Christopher Steele, which had circulated like samizdat among certain journalists and politicians for months, got a spectacular unveiling by BuzzFeed. Since then, though, the 35-page document’s highest profile has been as a source for Stephen Colbert’s wishful jokes about the existence of a Trump “pee pee tape.” Yet more and more of the dossier’s less-salacious raw intelligence, if not every detail, is turning out to be prescient and surprisingly accurate: that the Russians were peddling dirt on Hillary Clinton during the 2016 presidential campaign, for instance. A fresh sign of the dossier’s explanatory force is that, increasingly, it has become a target itself. Congressional Republicans appear to be trying to discredit Steele’s work as a way of undermining special counsel Robert Mueller’s investigation.

The House Intelligence Committee’s Republican majority has suddenly been firing subpoenas at the F.B.I. and its director, Chris Wray, plus the Department of Justice and Attorney General Jeff Sessions, demanding documents relevant to the F.B.I.’s relationship with Christopher Steele and to the bureau’s attempts to verify the information in Steele’s Trump-Russia dossier, which was originally compiled as oppo research for one of Trump’s Republican primary rivals.

Trey Gowdy, a South Carolina Republican, has claimed the subpoenas were necessary because the F.B.I. and D.O.J. haven’t cooperated with the committee’s less-formal requests. Some of his colleagues, however, believe they see a darker motive. “It’s an attempt to both delegitimize the dossier and delegitimize the F.B.I., particularly the work that was done under James Comey,” says Jim Himes, a Connecticut congressman who is the committee’s second-ranking Democrat. If Gowdy, who was in the running to be named U.S. attorney general by Trump, and his allies can tar the F.B.I.’s efforts as being founded in a political attack on Trump, it could help muddy the integrity of Mueller’s conclusions if the special counsel draws from the same pool of sources. (Gowdy could not be reached for comment.) “This is the latest installment of ‘don’t look there, look over here!’ ” Himes says.

Why all this new high-stakes maneuvering? Time and events have bolstered the dossier’s credibility. “The outline of Russian interference in the election that Steele had assembled by June 2016 was months ahead of what anybody else had gathered,” says John Sipher, a 28-year veteran C.I.A. officer who was stationed in Moscow at the same time Steele worked for British intelligence in Russia, and who wrote a detailed analysis of the dossier’s credibility for the blog JustSecurity. “Steele had raw, contemporaneous reports about meetings prior to June, and predicted stuff in the future he would have had no way to know. There’s some weird stuff in there, and things that can’t be verified. But Steele’s report identified multiple elements of the Russian operation including a cyber campaign, leaked documents related to Hillary Clinton, and meetings with Trump affiliates to discuss the receipt of stolen documents well before there was any public knowledge of these events. And the notion that the F.B.I. brought Steele in and was willing to pay him means they took his information seriously and that maybe it fit with some of the other things the bureau had collected.”

Gowdy’s tactics could have multiple ramifications for Mueller. “If you really have people who are seeking to undermine the F.B.I’.s investigation, even if they’re doing it for their own political reasons, it will help the Russians,” says Asha Rangappa, a former special F.B.I. agent who is now a dean at Yale’s law school. “There might be parts of the dossier that the F.B.I. has corroborated independently, and if you have a leaky committee, the Russians can try to cover their tracks and fabricate things to say, ‘Hey, that’s not true.’ They are not above that.”