New York City police have thrown up metal barriers around Trump Tower and blocked roads near Manhattan Criminal Courthouse as they brace for potential protests ahead of Donald Trump's expected surrender to prosecutors on Tuesday.

The former president is due to be arraigned at the courthouse Tuesday afternoon, after his indictment in a grand jury probe over hush money paid to a porn star. He is the first former U.S. president to face criminal charges.

Trump describes the probe as a political witch hunt, and top supporters, including Republican lawmaker Marjorie Taylor Greene, say they will go to New York on Tuesday to protest. The downtown courthouse, home to criminal and supreme courts, will shut down some courtrooms ahead of Trump's expected appearance, a court official said.