All the pieces appeared to be in place for Indiana Gov. Mitch Daniels (R). Party leaders had urged him to run for president and had pledged their support; the media wasn’t bashful in showing their affection for him; he had access to an extensive Bush fundraising apparatus; and he saw a path to victory, even boasting publicly about his chances.

But in the end, it appears Daniels just didn’t want to run. In an unexpected, overnight announcement, the Indiana governor announced his decision to a group of supporters.

Gov. Mitch Daniels of Indiana said Sunday that he would not become a candidate for the Republican presidential nomination, telling supporters in an e-mail message that concerns from his family were the overriding factor in deciding to stay out of the race.

“In the end, I was able to resolve every competing consideration but one,” Mr. Daniels wrote. “The interests and wishes of my family is the most important consideration of all. If I have disappointed you, I will always be sorry.”

The decision by Mr. Daniels answers one of the most highly-anticipated questions about the 2012 Republican presidential campaign, but introduces a fresh air of uncertainty into the race.

By all accounts, Daniels’ family discouraged him from running, which appeared to help dictate the decision.

The list of possible candidates who were considered contenders, but who ended up ruling out campaigns, has now well past double digits: Daniels, Huckabee, Barbour, Thune, Trump, Perry, Pence, Jindal, Corker, Jeb Bush, and Christie — and the list may yet grow. For all the Republican stated confidence about President Obama’s vulnerabilities, the fact that so many prominent GOP figures have decided to skip the 2012 race isn’t a great sign.

As for the larger implications of his announcement, Daniels did not yet have much of a support base, so it’s not comparable to Huckabee’s departure, with questions about where all of those backers will go. But for the Republican establishment, Daniels was already seen, not only as a Very Serious Person, but also as a top-tier contender.

Given the GOP insiders are already having heart palpitations about the weakness of the existing field, the Daniels news is likely to intensify the panic, and push party leaders to renew their efforts to recruit a “savior” candidate.

And speaking of the existing field, I imagine Pawlenty is pleased by the news (he’s eager to make this a two-person race with Romney); Romney will have a new chance to position himself as the frontrunner the party needs to rally behind; and Huntsman stands to benefit as the “serious” candidate, adored more by political reporters than primary voters.

Steve Benen

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.