Republican voters in the U.S. heartland state of Iowa on Monday gathered in school gyms, fire houses and churches to cast the first ballots in the 2024 White House race. 

The Iowa contest, known as a caucus, got under way at 7 p.m. local time on Monday (0100 GMT on Tuesday).

Donald Trump, the front-runner for his party's nomination, is expected to comfortably see off a challenge from former UN Ambassador Nikki Haley and Florida Governor Ron DeSantis in the first nominating test ahead of the November presidential election. 

(With input from agencies)