Mike Huckabee, by some measures, would have been the frontrunner for the Republican presidential nomination had he decided to run. But on his Fox News program last night, after dropping conflicting hints, the former Arkansas governor announced he will not be a candidate.

At the very end of his Saturday night show, Huckabee initially touted what a great presidential contender he’d be. He noted the polls that showed him in the lead; he touted support in the Northeast that “shattered the notion that I was only a regional candidate”; and he pointed to the support of his family members, who would be subjected to “brutal and savage personal attacks” if he ran. (Note to Huckabee: you’ve already run once, and no one bothered your family.)

But after explaining that the final decision was “a spiritual one,” Huckabee bowed out.

“All the factors say go, but my heart says no. And that’s the decision that I have made. And in it, I finally found some resolution. Now look, I don’t fully understand it myself, but I’m sure pundits will. But I do know this, that under the best of circumstances being president is a job that takes one to the limit of his or her human capacity. For me, to do it apart from an inner confidence that I was undertaking it with God’s full blessing, is simply unthinkable.

“I can’t know or predict the future, but I know for now my answer is clear and firm; I will not seek the Republican nomination for president this year. I’m going to gladly continue doing what I do and hopefully helping others in their campaigns for Congress, governorships, and other positions.”

At that point, for reasons that are unclear, the broadcast featured a “special announcement” from, of all people, reality-show host Donald Trump. “Mike Huckabee is not going to be running for president,” he said. “This might be considered by some people, not necessarily me, bad news because he is a terrific and, frankly, I think he’d be a terrific president. But a lot of people are very happy that he will not be running especially other candidates. So Mike, enjoy the show…. Good luck.”

The list of possible candidates who were considered contenders, but who ended up not running, is now nearly long enough to fill a baseball roster: Huckabee, Barbour, Thune, Pence, Jindal, Corker, Jeb Bush, and Christie — and the list may yet grow.

Also note, Huckabee’s 2012 endorsement just became one of the most important in GOP politics, and it was no accident that several Republican contenders, including the all-but-announced Jon Huntsman, promptly issued statements last night talking about how much they love and admire the Fox News personality.

Time will tell, of course, where Huckabee’s support goes in the existing GOP field, but his announcement immediately turns the Iowa caucuses into a free for all. Huckabee was the clear frontrunner in the Hawkeye State, and with him not in the race, the competition in the first caucus state will be even fiercer.

What’s more, it’s plausible that a variety of candidates will benefit in his absence. Romney now has less top-tier competition and may reevaluate the decision to deemphasize Iowa; Pawlenty will likely start characterizing the nominating contest as a two-man race; Daniels and Huntsman will tout themselves as plausible “savior” candidates saving the party from Romney and Pawlenty; and culture-warrior candidates — Santorum, Bachmann, Cain — now have a chance to break out of the bottom tier. Hell, Palin and Trump might even see Huckabee’s announcement as creating a void in the “outsider candidate” category that they’d like to fill.

As for Huckabee, he’ll remain at Fox News, maintain a radio presence, give plenty of paid speeches, continue to sell cringe-worthy education videos, and position himself as a right-wing kingmaker in GOP primaries nationwide. He’ll likely make lots of money, which Huckabee probably saw as preferable to losing another national race.

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Follow Steve on Twitter @stevebenen. Steve Benen is a producer at MSNBC's The Rachel Maddow Show. He was the principal contributor to the Washington Monthly's Political Animal blog from August 2008 until January 2012.