This could go down 1 of 2 ways.
Scenario 1:
Obama-Biden 404
Romney-Ensign 134
In the aftermath of the September 15th Financial Collapse, Obama is able to portray Romney as a puppet of Wall Street, which hurts him in working-class states like Indiana, Wisconsin, Ohio, Pennsylvania, and Michigan. His pick of Nevada Senator John Ensign for VP did nothing tho help that image either. And his Mormon religion hurts him in the South, depressing turnout and putting Georgia and Missouri into Obama's column. The race mirrors 1988 in the electoral college votes, and Romney is looked back upon as Michael Dukakis the Second Coming.
Scenario 2:
Obama-Biden 322
Romney-Pawlenty 216
Romney runs as a businessman who knows how the economy (and more importantly,Main Street) works. He runs to the center and picks Governor Tim Pawlenty as his running mate as a play to working-class whites. His message resonates better McCain's (not enough to win, but it makes the race closer) picking up Indiana, Florida, and New Hampshire.