There's an article at Politico enumerating why Obama supporters should be worried. Some of the reasons to worry are accurate (race issues, Virginia, and Michigan are all X-factors) and some are silly (the fact that Dems have only elected Southern governors to be President in the last half-century, there's no third party challenger, people may want divided government). One other concern is more wishy-washy: the claim that because people believe the country is going in the wrong direction, they will seek the stability of John McCain. They could just as easily link McCain to Bush policies and want change.
But of course, the real item for chattering class discussion is the gossip that Hillary Clinton is telling her supporters she has "doubts" about Obama. Classy. And self-described Obama supporter Bob Kerrey is telling Politico that "there's some uncertainty about Senator Obama” and "[voters] want change, but I'm not sure that the Democratic agenda has the support of a majority of Americans." Some supporter. The latter statement doesn't really have much to back it up -- polling does suggest that the Democratic agenda is favored by a majority of voters -- but the former observation is certainly giving Obama some worry.
One other note -- the only person quoted on record in this piece is Kerrey. I've noticed a lot of Politico articles rely heavily on unidentified sources, and some of them -- especially this John Bresnahan piece suggesting that House Dems are disappointed in the Obama campaign -- don't seem to carry much water. Thoughts?
--Tim Fernholz