Former Massachusetts Gov. William Weld, a Republican, endorsed Democrat Barack Obama for president on Friday, citing the senator’s good judgment, “deep sense of calm” and “first-class political temperament.”

Weld said he’s never endorsed a Democrat for president before, but in the last six weeks or so, it became “close to a no-brainer.” Obama has a history of bringing Democrats, Republicans and independents together and is the best choice at a time when America’s standing in the world is at a low point, he said.

“It’s not often you get a guy with his combination of qualities, chief among which I would say is the deep sense of calm he displays, and I think that’s a product of his equally deep intelligence,” he said in a phone interview.

I’m a little surprised by this one. Bill Weld has always been a more moderate Republican, but he was once considered a rising star in the GOP. Earlier this week, former Minnesota Gov. Arne Carlson also endorsed Obama. Carlston was also a moderate Republican governor. It’s telling that both of them are willing to buck their party and endorse Obama.