Donald Trump cast his ballot at a recreation centre in Palm Beach, Florida, before he told reporters that his former adviser Peter Navarro was treated “unfairly” by the Biden administration.
Florida was one of five states holding presidential primaries on Tuesday 19 March as Joe Biden and Mr Trump continue to lock up support around the country after becoming their parties’ presumptive nominees.
Navarro 74, was convicted last year after ignoring a subpoena from a House committee investigating the 6 January 2021 Capitol riot.
He began a four-month jail term for contempt of Congress in federal prison on Tuesday.
The former president criticised Navarro’s treatment as he left the polling station, calling it a “shame” and a “disgrace” to the nation.