Cole Allen, the suspect in the White House Correspondents' Association dinner shooting, pleaded not guilty to all charges on Monday.
Allen, 31, of California, did not speak in court as his attorney entered the plea on his behalf, facing charges including attempted assassination of the president and firearms offences.
Prosecutors allege Allen fired a shotgun at a US Secret Service agent and stormed a security checkpoint in a foiled attack on Trump and other administration members.
Allen's lawyer, Eugene Ohm, said the defence will seek recusal of the entire US Attorney's Office in Washington due to the acting Attorney General's and US Attorney's presence at the dinner.
The defence claims it is inappropriate for victims of the alleged event to prosecute the case, with prosecutors set to respond to the defence's filing by May 22.