Rhode Island Gov. Lincoln Chafee (D) surprised the political world Wednesday when he announced that he will not run for a second term. And for Democrats with an eye on holding the governor's mansion in Rhode Island, it was a pleasant surprise.

(Stew Milne/AP)

To be clear, Democrats have been heavily favored to win in Rhode Island ever since Chafee, a former independent, joined the Democratic Party in May, and eliminated the possibility of a three-way vote split that would have upped the odds of a Republican upset. The decision he announced Wednesday means the seat is even less likely to flip. There are three reasons why:

1. Chafee was damaged political goods. Chafee is unpopular in Rhode Island. Plain and simple. Now, Democrats don't have to worry about nominating such an unpopular figure the general election. There are two Democrats expected to run -- state Treasurer Gina Raimondo and Providence Mayor Angel Taveras -- who each look like stronger prospects for the general election, because they aren't weighed down by Chafee's baggage.

2. A less bruising primary. When Chafee became a Democrat in May, it looked like an apparent last-ditch effort at political survival. He seemed to be reasoning that his odds in a contested Democratic primary and the general election (if he made it that far), would be better than rolling the dice in potentially competitive three-way general election campaign against Democratic and Republican nominees. And maybe they would have been. But win or lose, the primary promised to be expensive and bruising. And that could have left the eventual  Democratic nominee cash-strapped and tending to wounds caused by a nasty campaign. It's true that with Chafee out of the picture now, the Democratic field may grow more crowded than it would have been with him in the race. But it's hard to imagine a more negative primary than one in which party-switching, unpopular incumbent is in the mix.

3. President Obama is no longer entangled. For Chafee, part of the upside of becoming a Democrat was his relationship with President Obama, a close friend from their days in the Senate. (Chafee endorsed Obama early in the 2008 presidential primary.) Obama welcomed Chafee to the Democratic Party with open arms in May, all but endorsing his candidacy. So why is this an issue? Recall that in 2010, Obama's refusal to endorse Democratic nominee Frank Caprio against Chafee prompted Caprio to say that Obama could "shove it." It was the kind of Democratic infighting that wasn't good for the party. Given Obama's footprint, it's possible some discord could have erupted again in 2014, had Chafee kept his campaign going.