The way I see it Romney had three paths to victory.
One: Win FL, OH and VA plus one smaller swing state.
This was by far the most likely path Romney would've took if he were to have won. FL+OH+VA+either CO or IA seemed to be the most viable path for Romney in particular.
Two: Upper Midwest
OH was always in doubt. Romney also thought he needed a backup plan in case he lost OH. This is where the upper midwestern path comes to light with Romney squeezing out narrow wins in IA and WI while also winning VA, CO and FL making OH irrelevant. NV and NH are gravy.
Three: 2004 Redux
This would've been the 2004 map except NM goes solidly Obama and Obama ekes out a win in Ohio but Romney wins in NH, a state where Romney hoped his Northeastern coattails could've handed him a victory. He would've also needed to have won Nevada. Obama wins by a very narrow margin in WI while Romney squeaks out a Bush 04' margin of victory in IA.