CONCORD, N.H. — Republican presidential front-runner Donald Trump told hundreds of New Hampshire voters Monday that he will announce a "big endorsement" in the next 24 hours.

"We're getting a big endorsement on Tuesday. It's going to be a lot of fun," the self-funded billionaire told a crowded high school gym, declining to go any further.

Trump is set to arrive in Iowa early Tuesday morning for a rally at the birthplace of famed Western film actor John Wayne, who's daughter recently endorsed the New York businessman in a letter posted to his Facebook page.

The leading GOP candidate has received endorsements from a handful of celebrities, state lawmakers and a New England police union since he launched his presidential bid in mid-June. Still, Trump has yet to earn the endorsement of any congressional leader or member of the U.S. Senate.