The 10-point difference between Obama and Romney suggests about an Eisenhower-scale electoral blowout. Romney picks up about 2% from the would-be Dobbs voters, Obama picks off about 2% from the would-be Nader voters (49-39), and half the undecided stay home (49-39-3-2) or vote like the 'decided' voters, so in the end it ends up 52.6-41.9.
Because Obama has maxed out support in the Blue Firewall states he can have gained only in those states that were close (examples: Georgia, Missouri, and Montana; maybe North Carolina, Ohio, and Florida) and those in which Obama was absolutely crushed in 2008 (like Kentucky, Tennessee, Texas, and West Virginia).