The motion amounts to the most pointed attack yet by defense lawyers on the federal case charging Trump with plotting to overturn the results of the 2020 presidential election he lost to Democrat Joe Biden. In it, they argue that the actions that form the basis of the indictment, including urging the Justice Department to investigate claims of voter fraud and pressing state officials on the administration of elections, cut to the core of Trump’s responsibilities as commander in chief.

“Breaking 234 years of precedent, the incumbent administration has charged President Trump for acts that lie not just within the ‘outer perimeter,’ but at the heart of his official responsibilities as President,” the defense motion states. “In doing so, the prosecution does not, and cannot, argue that President Trump’s efforts to ensure election integrity, and to advocate for the same, were outside the scope of his duties.”

The presidential immunity argument had been foreshadowed for weeks by defense lawyers as one of multiple challenges they intend to bring against the indictment, among the four criminal cases Trump is facing.

Special counsel Jack Smith’s team had appeared to anticipate the argument as well, saying in the indictment that though political candidates are permitted to challenge their election losses, Trump’s actions strayed far beyond what is legally permissible.

Prosecutors are expected to contest the motion.