The Republican White House hopefuls are preparing to do battle in the first debate of the 2024 primary contest on Wednesday — with Donald Trump set to upstage his rivals despite his decision not to show up.

Five months ahead of the start of primary elections to choose the party's flag-bearer, the runaway front-runner's grassroots support is as strong as ever, but numerous criminal cases are overshadowing his comeback bid.

The 77-year-old former president, who is rarely out of the headlines, revealed on Sunday he would be skipping the event in the city of Milwaukee, Wisconsin, wary of sharing the limelight with lower-polling rivals.