Huntsman, a former Utah governor, quit his post last year as President Obama's ambassador to China to make a surprise entry into the 2012 race. But that diplomatic credential wound up working to his disadvantage in a Republican contest driven largely by the party's desire to unseat the Democratic incumbent in the White House.
His decision to drop out came on the eve of a potentially decisive round of debates and primary voting in South Carolina and Florida, with Romney poised to lock up the nomination. It is unlikely that Huntsman's endorsement will have a significant effect, given his anemic support from GOP voters.
Huntsman positioned himself to the left of the former Massachusetts governor, skipping the Iowa caucuses — dominated by social and religious conservatives seen as unfriendly to his moderate brand of conservatism — and betting everything on New Hampshire.
Huntsman's experience in foreign policy outstripped any of his rivals, but his work overseas wasn't much help when the struggling domestic economy was the top issue for voters.
The 51-year-old scion of a wealthy Salt Lake City family — his billionaire father pumped money into a "super PAC" that advertised on his behalf — fell flat in New Hampshire, despite holding more campaign events than any of his rivals. He finished a distant third in last Tuesday's New Hampshire primary, with barely 17% of the vote.
To the surprise of many, Huntsman announced on primary night that he would plunge ahead anyway into South Carolina. But the conservative Southern state was hardly fertile territory for the patrician Westerner, and it soon became clear that he lacked any hope of a rebound.