Mr DeSantis's decision comes less than a week after his crushing defeat to Mr Trump in Iowa, despite a huge investment in the state. It also means Nikki Haley is now Mr Trump's only remaining challenger in the race for the Republican nomination.

This is seen as a big surprise after Governor Ron DeSantis was widely seen as the most promising Republican alternative to Mr. Trump in the US general election this November.

A majority of DeSantis supporters are more likely to switch to Trump than Haley. In New Hampshire, about two-thirds of DeSantis supporters see Trump as their second choice, according to Andrew Smith, director of the University of New Hampshire Polling Center.

In a video posted on X, Mr. DeSantis also announced his endorsement of Mr. Trump. According to polls, Mr. Trump also has a double-digit lead over Ms. Haley in New Hampshire, thereby firmly confirming that he will be the Republican Party's nominee in the US presidential race with the Democratic Party later this year.

In a statement following Mr. DeSantis’s announcement, Mr. Trump’s campaign thanked him for his endorsement and urged Republicans to unite behind him. The winner of the Republican nomination will likely face President Joe Biden, the presumptive Democratic nominee.

Hoang Anh (according to Reuters, CNN)