I don’t agree with everything Jay Cost says here but these five points strike me as spot-on:

(1) The macro conditions favor the Democrats in a way we have not seen in at least 28 years.

(2) In response, the Democrats nominated a candidate with relatively little governing experience and a background quite different from white voters, who swing presidential elections.

(3) The Republicans nominated a candidate who built a national reputation by disagreeing with George W. Bush in particular and the Republican Party in general, in the hopes that this man is immune from the public disaffection with the GOP.

(4) The public now gets to choose a man with little experience and a different background, or a semi-Republican. They’re not sure which one they want. And because there are two wars on, a credit crisis, a weak economy, and high gas prices – they’re taking their sweet time in deciding.

(5) Anybody who tells you what is going to happen is probably trying to sell you something.

My only minor quibble would be that the Republicans nominated McCain more by accident than as part of some master plan and the Democrats nominated Obama in no small part because the more experienced Democrats had been too timid to oppose the war in 2002-03.