He endorsed Obama in 2008 and spoke at the Democratic convention last year. It was a fait accompli. Charlie Crist is the Ghost of Party-switchers Past and Jon Huntsman is the Ghost of Party-switchers Future; now, at last, we can complete the triad.

His decision to switch from GOP to indie was a matter of principle, I think — namely, the principle that he apparently can’t stand conservatives. This switch is more strategic.

The officials said Chafee plans to change his registration to join the party. They weren’t authorized to disclose the information publicly ahead of any announcement from Chafee and spoke on condition of anonymity. Chafee’s staff did not immediately confirm his plan.

Chafee has been saying for months that he was thinking about the switch, noting that he shares many positions with Democrats and that joining the party will help with fundraising. He is a supporter of President Barack Obama and spoke at last year’s Democratic National Convention.

The move further complicates next year’s Democratic primary and sets up the possibility of a three-way matchup with Providence Mayor Angel Taveras and Treasurer Gina Raimondo.

Thanks to Rhode Island’s terrible 9.8 percent unemployment rate, his approval rating is 28/68, rock bottom for any U.S. governor in a state that’s voted Democratic in every presidential election except one since 1976. Obvious question: Why would a guy who’s pulling -40 in job approval want to put himself through a tough primary when he could remain an independent and proceed directly to the general election? The answer, I think, is the same answer Arlen Specter reached three years ago in switching to the Democratic Party instead of going indie. Quite simply, he can’t win a three-way race in the general with Republicans and Democrats turning out en masse for their party’s respective candidates. Crist tried that against Rubio in 2010 and got destroyed because Kendrick Meek, the Dem nominee, refused to drop out and ended up peeling off enough Democratic voters who might otherwise have gone for Crist that Rubio was able to waltz to victory. Chafee’s odds of reelection are better if he braves a primary and hopes against hope that the economy picks up in time to propel him to the win, at which point most of the state’s Democratic majority will fall in line behind him. Winning as an independent is hard even under the best circumstances. Under the worst circumstances, forget it.

I wonder if the Democrats offered him anything to make the switch. This is, after all, in their interest:

Chafee’s decision is good for Democrats for a couple of reasons. One, it takes off the table the threat of a vote split between the Democratic nominee and the governor, something that could open the door for the Republican to win, even in a Democratic-leaning state. If Chafee loses the Democratic nomination — and it is hard, at least at this point, to see him winning — then he is out of the picture altogether. Of course, if he wins, Democrats would have to back a pol with a struggling image in the eyes of Republicans.

Maybe O’s got a vacant ambassadorship tucked away somewhere for him to fall back on in case things don’t work out.

And now, in honor of the party-switch, a ceremonial playing of the “No Labels” anthem. Tick tock, Jon Huntsman.