On the one hand, this is definitely unusual, since office-holding Democrats tend to support their own party's nominee. But, then again, Manchin is up for reelection this year in West Virginia, a place where the people refer to the president as "Barack Hussein Obamer," probably. He doesn't have a lot to gain from being a gung-ho Obama supporter. Also, this is the guy who literally shot cap and trade in an ad last year, with a gun. This should not be unexpected.