Lawyers for Donald Trump on Thursday asked a judge to dismiss the case against him in the federal election in Washington, arguing that the Republican is immune from prosecution for actions they say were taken in his official role as president.

The motion amounts to the sharpest attack yet by lawyers on the federal case accusing Trump of plotting to overturn the results of the 2020 presidential election that he lost to Democrat Joe Biden. In it, they argue that the actions that form the basis of the indictment, including pushing the Justice Department to investigate claims of voter fraud and pressuring state officials to administer elections, go to the heart of Trump’s responsibilities as commander in chief.

Breaking a 234-year precedent, the incumbent administration has indicted President Trump for actions that are not merely borderline, but core to his official responsibilities as president,” the defense motion said. In doing so, the plaintiff does not: and cannot allege that President Trump’s efforts to ensure and advocate for election integrity fell outside the scope of his duties.

The presidential immunity argument had been predicted for weeks by lawyers as one of several challenges they plan to bring against the indictment, one of four criminal cases facing Trump.

Special counsel Jack Smith’s team also appeared to anticipate the argument, saying in the complaint that while political candidates are allowed to challenge their election losses, Trump’s actions went far beyond what is legally allowed.

Prosecutors are expected to contest the motion.