The Florida governor posted a four-minute vid to X telling his supporters he's suspending his campaign -- this, just two days before the New Hampshire primary -- and ultimately he's putting his support behind former President Donald Trump.

RD started his clip by repeating many conservative stances on issues -- more border security, social decay in cities, indoctrination of children by woke ideology ... basically the boilerplate message.

DeSantis said his team prayed after the loss in Iowa -- where Trump crushed him at the voting booths, with more than double Ron's vote count -- and his team ultimately realized there's nothing that'll swing the race in their favor.

As for the endorsement ... the 45-year-old acknowledged he's disagreed with DT on policy in the past, but he's putting that aside for the good of the party -- basically saying four more years of Joe Biden in the White House isn't acceptable.

Hitching your wagon to the frontrunner ain't anything new in politics -- it's all part of the game. And RD's stayed away from roasting Trump during the run-up to the primaries ... unlike Nikki Haley, the last major opposition to the Donald.

Speaking of NH, it's not surprising she's not getting Ron's support ... not only did she finish third in Iowa and fall way behind Trump in the polls, but they faced off at the last Republican debate -- and it got a little nasty.

Ron said Nikki's only in it for what her financial backers want ... Nikki straight up called Ron a liar -- yeah, it got pretty intense.