A judge in Atlanta threw out three charges in the Georgia election interference case against Donald J. Trump and his allies on Thursday, saying the state did not have jurisdiction to bring them.

In a separate ruling, the judge, Scott McAfee of Fulton County Superior Court, also upheld the felony racketeering charge against Mr. Trump and the 14 other defendants in the case — the centerpiece of the indictment — calling it “facially sound and constitutionally sufficient.”

But the decision to toss three of the remaining 35 charges was a win for the defendants, who have been trying to chip away at the case. They are also seeking the disqualification of its prosecutor, Fani T. Willis, the Fulton County district attorney.

Ms. Willis’s office originally brought 41 counts against 19 defendants in August 2023. Four defendants have since pleaded guilty, and Judge McAfee previously quashed six of the charges.

While Judge McAfee rejected the effort to disqualify Ms. Willis earlier this year, the defense then appealed, freezing much of the case in the interim. Because of the ongoing disqualification effort, the rulings on Thursday applied only to two defendants who aren’t part of that effort: John Eastman, an architect of the plan to deploy fake electors in seven swing states that Mr. Trump lost in 2020, and Shawn Still, one of those fake electors.

But the rulings will almost certainly be extended to other defendants when the disqualification question is resolved. As a result, Mr. Trump, who originally faced 13 charges, is now likely to face eight.