A federal judge on Thursday blocked Republican Texas Attorney General Ken Paxton from continuing to pursue a lawsuit against the Democratic fundraising platform ActBlue over its donation practices, saying he was retaliating against it for fundraising on behalf of his opponent in the race for U.S. Senate seat.

U.S. District Judge Richard Stearns in Boston issued a preliminary injunction at the behest of ActBlue, which argued Paxton infringed its free speech rights by suing the organization in April while campaigning against Democrat James Talarico for a Senate seat up for grabs in November’s election.

(Reporting by Nate Raymond in Boston; Editing by Chris Reese)