The enthusiasm gap, highlighted by Steve Benen:
McCain is lagging in enthusiasm. Forty-nine percent of Obama voters describe themselves as “very enthusiastic,” compared to just 21% of McCain backers, and a full 27% of the Republican nominee’s supporters say they are either “not very” or “not at all” enthusiastic about him, compared with 10% for Obama.
Pray that it rains on election day in the swing states. Obama people will go through fire and flood to vote for him. McCain people? "Eh, its raining, best just stay home."