ALEXANDRIA, Va. >> A federal judge ruled today that prosecutors cannot present evidence to a jury about the most salacious parts of a flawed dossier alleging connections between former President Donald Trump and Russia at an upcoming trial of an analyst who served as a primary source for that report.

Igor Danchenko is scheduled to go on trial next week in U.S. District Court in Alexandria on charges of lying to the FBI. Special Counsel John Durham says Danchenko was a primary source of information in a dossier about Trump prepared by British spy Christopher Steele at the request of Democrats during the 2016 presidential campaign.

The indictment alleges that Danchenko’s primary source of information was actually a Democratic operative named Charles Dolan, a public relations executive who volunteered for Trump’s opponent, Hillary Clinton. Prosecutors say the FBI would have been able to judge the veracity of the dossier more accurately if Danchenko had admitted his primary source was a Clinton supporter.

The dossier most famously includes allegations that Trump engaged in salacious sexual activity with prostitutes at a Moscow hotel that was purportedly bugged by Russian intelligence — raising the possibility that Russians had information they could use to blackmail Trump.

Trump had called the dossier fake news and evidence of a political witch hunt against him.

The five specific counts in the indictment don’t charge Danchenko with lying about his sourcing for the sex allegations. Still, prosecutors wanted to present testimony at trial that they said would have shown that Danchenko lied about his sourcing for those allegations just as he lied about other aspects of his sourcing,

Danchenko’s lawyers objected. They say the testimony would be highly prejudicial and would confuse the jury.

In a ruling issued today, U.S. District Judge Anthony Trenga agreed with the defense. Specifically, he said the testimony that the government planned to introduce wouldn’t actually prove Danchenko lied.

“(G)given the low probative value of these allegations, they are not admissible … as they are substantially outweighed by the danger of confusion and unfair prejudice,” Trenga wrote.

The ruling is another setback for Durham’s case. At a hearing last week, Trenga rejected a motion from Danchenko’s lawyers to toss out the case entirely. But in doing so, he said it was “an extremely close call” and said jurors may well be persuaded by Danchenko’s defense.

Danchenko’s lawyers have called the case an example of prosecutorial overreach and have said that the answers Danchenko gave to the FBI were all technically true, even if they weren’t particularly illuminating.

Also in today’s ruling, Trenga denied — at least for now — a request from the government that Danchenko be barred from arguing to jurors or presenting evidence that the prosecution is politically motivated.