If Romney campaigns in MN it wont look like he is a momentum candidate expanding the map, it will look like he is a desperate candidate trying to find a path around Ohio.
Seriously?
1) I think any rational person will agree that if Romney wins Minnesota of all states, he wins Ohio with ease. Minnesota is a tier 2 state to any Republican win. (Akin to NC going into the D camp, you'd be looking at a 300-350 EV scenario).
2) Virginia is pretty much closed off to campaigning for a few days.
3) It's not like Romney can't do a MSP-suburbs/pick a city in Wisconsin two-stopper with ease.
4) Any trip into the MSP area, will be beamed into Northwestern WI. It's a two-fer.
5) Expanding the map and making your opponent play defense is NOT a bad tactic. Especially when your opponent may be stuck in DC for a few days being President.