Time magazine has these 8 items as key to the 2008 Presidential Election:

“8 Keys to ’08 Campaign”

1. Iraq
2. Money
3. Religion
4. Amazon Factor
5. Last Minute Campaigns
6. Operatives
7. Blogosphere
8. New Faces

Not sure that I agree that number of books sold or ones religion are the keys to winning the seat but they seem to be right on the other elements.