The former President was at the Miami federal courthouse Tuesday, where a crowd of protesters gathered out front earlier in the day -- some in support of Trump's indictment, while others continue to defend his claims of innocence.

He was spotted Monday leaving his Trump National Golf Club in Bedminster, NJ on his way to Florida -- and he's reportedly going to head back there to give a speech regarding the case later tonight.

Trump was also posting on Truth Social on the way to the Miami courthouse early Tuesday morning -- calling it "one of the saddest days in the history of our country" ... adding it's a "WITCH HUNT!!!"

As we reported, DT's prosecutors claim he stored a ton of classified docs wherever he could at his Palm Beach resort -- photos showed piles of boxes stacked on a ballroom stage, a storage room, and even next to a toilet.

The feds say he housed information regarding defense and weapons capabilities of both the U.S. and foreign countries, U.S. nuclear programs, and other highly sensitive material about potential vulnerabilities of the country and its allies to military attacks.

According to the indictment, Trump's been hit with whopping 31 counts of willful retention of national defense information.

As for the other six counts, he's facing separate charges for false statements and representations, conspiracy to obstruct justice, withholding a document or record, corruptly concealing a document, concealing a document in a federal investigation, and a scheme to conceal.

We spoke with Loyola Law School professor Jessica Levinson, who told us why his latest indictment shouldn't have the ability to stop his 2024 campaign trail -- and she says he shockingly could even serve as president behind bars.

For those unaware, Trump announced the indictment on Truth Social before the docs were even unsealed -- and of course, he claimed total innocence.