Here are the scenarios:
Romney takes all the McCain 2008 states, plus NC VA FL IN CO. This yields 257 EVs. Then only one of the following must be won for a Romney victory:
1. OH(18) -or-
2. PA(20) -or-
3. MI(16) -or-
4. MN(10) + [NH(4) or IA(6) or NV(6) or...] -or-
5. WI(10) + [NH(4) or IA(6) or NV(6) or...] -or-
6. NV(6) + IA(6) (the tie scenario).
Unfortunately Romney had to spend so much time winning back FL and VA, which McCain/Bush lost in 2008, that he didn’t have time to get out to these swing states and earn a clear lead.