A California man accused of attempting to assassinate U.S. President Donald Trump at last month’s White House Correspondents’ Dinner has pleaded not guilty to all charges.

The suspect, Cole Allen, 31, appeared in a Washington federal court on Monday wearing an orange prison jumpsuit and restraints. His attorney, Tezira Abe, entered the plea on his behalf while Allen remained silent during the hearing.

Allen faces multiple charges, including attempted assassination of the president, assault on a federal officer, and firearms-related offences. Prosecutors allege that he fired a shotgun at a U.S. Secret Service agent and attempted to breach a security checkpoint during what authorities described as a failed attack targeting Trump and members of his administration.

Investigators claim Allen travelled from California to Washington by train carrying a shotgun, pistol and knives, and had booked a room at the Washington Hilton hotel, where the April 25 White House Correspondents’ Dinner was held.

The hearing marked Allen’s first appearance before U.S. District Judge Trevor McFadden, who is expected to oversee the remainder of the case.

The case is also expected to involve legal challenges from the defence seeking the removal of acting Attorney General Todd Blanche and U.S. Attorney Jeanine Pirro from the prosecution, arguing that both attended the dinner and could be considered potential victims.

Allen’s lawyer, Eugene Ohm, said the defence may seek the recusal of the entire U.S. Attorney’s Office in Washington, citing Pirro’s relationship with Trump and her presence at the event. Prosecutors are expected to respond to the motion by May 22.