Donald Trump arrived at a federal courthouse in Florida for a closed hearing in his criminal case charging the former US President with mishandling classified documents.

The hearing on Monday morning was scheduled as a procedural hearing, closed to the public, to discuss the procedures for handling classified evidence in the trial currently set for May 20.

US district judge Aileen Cannon set arguments in the morning from defence lawyers and in the afternoon from prosecutors, each outside of the other’s presence.

Trump Classified Documents
Supporters of former US President Donald Trump stand near the US Federal Courthouse in Fort Pierce (Marta Lavandier/AP)

Supporters with signs and flags assembled outside a courthouse barricade as a Trump campaign message to allies with the subject line of “I’m in court. Again!” warned that unspecified opponents “want me arrested” and “erased from the ballot”.

The message reinforced his team’s strategy of politicising his four criminal prosecutions, including in Florida, where he faces dozens of felony counts accusing him of hoarding highly classified records at his Mar-a-Lago estate as well as obstructing FBI efforts to get them back.

“Defence counsel shall be prepared to discuss their defence theories of the case, in detail, and how any classified information might be relevant or helpful to the defence,” Cannon wrote in scheduling the hearing.

It comes as prosecutors have also revealed that a prospective government witness has received threats over social media that are now the subject of federal investigation.

Mr Trump’s motorcade arrived at the courthouse in Fort Pierce shortly after 9am.

Donald Trump is pictured (Manuel Balce Ceneta/AP)
The hearing is one of several voluntary court dates that Mr Trump has attended in recent weeks (Manuel Balce Ceneta/AP)

He left the building in his motorcade after 2pm while supporters shouted his name.

The hearing is one of several voluntary court dates that Mr Trump has attended in recent weeks, including appeals court arguments last month in Washington, as he looks to demonstrate to supporters that he intends to fight his criminal prosecutions while also seeking to reclaim the White House in November.

In addition to the Florida case, Mr Trump faces charges in Atlanta and Washington related to efforts to overturn the results of the 2020 presidential election.

He’s also charged in state court in New York in connection with hush money payments made to porn actor Stormy Daniels.

Mr Trump has denied any wrongdoing.