And then there were five. That's the number of GOP presidential hopefuls left standing after Jon Huntsman dropped out of the race on Monday to throw his support behind frontrunner Mitt Romney. Huntsman had wagered his entire campaign on a strong showing in the New Hampshire primary, and his third-place finish wasn't enough to give him the injection of momentum and campaign cash he needed to boost his prospects in South Carolina and Florida. Unlike previous GOP dropouts this year, Huntsman didn't suffer from bad press (Michele Bachmann) or no press (Gary Johnson). In fact, Huntsman was the subject of several flattering magazine profiles, and just Sunday, he won the endorsement of South Carolina's biggest newspaper, The State. So why did Huntsman's campaign fail to launch? Here, five theories:

1. Huntsman ran as a moderate in a year of revolt
The former Utah governor was "a relative moderate running in a bull market for conservatives," says Alex Altman at TIME. Instead of focusing on his governorship, in which he racked up "a conservative record on fiscal issues, abortion, and gun rights while presiding over a surge in job growth," Huntsman talked like a moderate, "bucking GOP doctrine on issues like global warming" and serving a GOP electorate hungry for red meat "a steady diet of civility and compromise." Republicans can't agree on much this year, says David Weigel at Slate, but they clearly "had no interest in a compromise candidate who could speak Democratic parseltongue."

2. He was too much like Romney
Huntsman may be out of step with today's conservative GOP, but let's face it: "A moderate is probably going to win the Republican presidential nomination" this year, says Erica Grieder at The Economist. If anything, Huntsman's real problem is that he is too similar to Romney, and was campaigning for the same voters: "Moderate Republicans and independents, the business conservative crowd, pragmatic people, people who aren't frightened about Mormons." Unfortunately for Huntsman, "Romney had a head start of four years and millions of dollars."

3. Huntsman worked for Obama
Huntsman has a solid record of serving Republican presidents, says James Antle at Britain's The Guardian, but "the most recent line in his résumé was, in the eyes of many Republicans, disqualifying: Ambassador to China under President Barack Obama." Huntsman tried to sell his ambassadorship as putting "country above party." Republican voters disagreed, seeing it as "an act of disloyalty, or worse, putting power before principle." And they have a good point, says Chris Lawrence at Outside the Beltway. There's a reason virtually all politicians who opt to serve a president of the other party do so "at the conclusion of their partisan political careers."

4. He counterproductively antagonized conservatives
When Huntsman "casually tweeted about his belief in evolution and climate change," using snarky quips like "Call me crazy," it turns out that "many conservatives felt that Huntsman was actually calling them crazy," says Antle. Huntsman failed to realize that after serving Obama, he had to court the Right, not ridicule it. For whatever reason, he "talked like a centrist who despised conservatives," says Ed Morrissey at Hot Air. "Huntsman's expensive and embarrassing flop really isn't much more complicated than that."

5. Huntsman just isn't a great national politician
Huntsman never squared the key contradiction of his campaign: Pushing "very conservative" economic policies with a big play for moderates and independents, says E.J. Dionne at The Washington Post. "As a result, his message was mixed and his appeal was muddled." He had other problems, too, says Kevin Drum at Mother Jones. Huntsman thought "quoting a bit of Chinese in the last debate counted as a devastating riposte." Let's not sugar-coat this: "The story here is that Huntsman just isn't that great a politician." You could probably say that about "any capsized candidacy," says The Economist's Grieder. But yes, some people "seem to have a magic touch for national politics," and Huntsman didn't.