Donald Trump addressed his supporters on Saturday for the first time since his indictment on multiple federal charges propelled the 2024 presidential election race into uncharted and potentially destabilising territory.

The 37 counts of the indictment – released on Friday and focused on his alleged mishandling of classified materials – set the former president up for a far more severe legal reckoning than the charges of personal, political and commercial misconduct he has largely ridden out in the past.

And it also sets the stage for a White House race like no other before it, with US President Joe Biden's Department of Justice pursuing the prosecution of the clear front-runner for the Republican nomination.

Trump, who has already denounced what he insists is a politically-motivated witch hunt, is talking at two state Republican conventions in Georgia and then North Carolina, and was widely expected to use both platforms to attack the FBI and accuse federal prosecutors of unfairly targeting him.

In Columbus, Georgia, Trump railed against Biden and the Department of Justice and what he called a "fake indictment," telling the crowd he was being pursued in court because of his bid for a second term in the White House.

"That's why they're doing it, if I wasn't, there would be no witch hunt, there would be no indictment," he told supporters.

The two events come just days before Trump is due to appear in federal court in Miami to answer the explosive charges he put US national security "at risk" by willfully retaining classified defense information, conspiring to obstruct justice, corruptly concealing documents, and making false statements.

The charges, brought by Justice Department Special Counsel Jack Smith, carry up to 20 years in prison each. (AFP)