Florida Governor Ron DeSantis suspended his campaign for the Republican presidential nomination on Sunday, saying he would throw his support behind frontrunner Donald Trump.

In a video posted to X, formerly Twitter, DeSantis said that after his second place finish last week in the Iowa caucuses he could not "ask our supporters to volunteer their time and donate their resources if we don't have a clear path to victory. Accordingly, I am today suspending my campaign."

His withdrawal from the race comes less than two days before the New Hampshire primary, where polls showed him far behind ex-president Trump and former UN ambassador Nikki Haley.

"It's clear to me that a majority of Republican primary voters want to give Donald Trump another chance," DeSantis said in the video, noting he has had differences with the former president, notably over the coronavirus pandemic.

"He has my endorsement because we can't go back to the old Republican guard of yesteryear or a repackaged form of warmed-over corporatism that Nikki Haley represents."

Trump, 77, stormed to victory in Iowa last Tuesday, with 51 percent of Republican voters choosing the twice-impeached former president over DeSantis, who gained only 21 percent, and Haley at 19 percent.

No candidate has ever lost the race after claiming the first two states, and Trump would almost certainly declare the Republican nomination over with a win in New Hampshire.

Haley had largely refrained from hitting out at Trump's many controversies surrounding his candidacy, but in the past week began questioning his mental acuity, making comparisons between the ex-president and the 81-year-old incumbent Democrat Joe Biden.