Here's the challenge.
Keeping the economic situation exactly as it occurred historically, devise a scenario in which McCain beats Obama in 2008.
Assume that assassination is off the table, and Obama does not have any health, personal, or other disqualifying issues other than what he historically had (for example, your strategy can include better attacks re: Jeremiah Wright/Bill Ayers, but cannot include Obama cheating on his wife).
Any other changes are perfectly acceptable, with a Point of Divergence at any point during the campaign, including primaries (but both men end up as the nominees).
Is this possible?