I am pretty sure Romney will win, probably by 3-4.
The GOP took the state in historic fashion in 2010. The Dems were wiped out for their big spending ways, on the state and federal level (took both House seats and US Senate seat... and over 400 state house seats).
Since then, unemployment in the state is higher and gas prices are up. And we had a Dem governor - so there is no way to blame the GOP (although they are trying).