I'm not sure where this idea that the industrial midwest is trending GOP comes from. The Appalachian foothills in SW PA & SE OH, maybe, but the rest of the region?
If anything, I suspect that the Tea Party backlash will be less strong in the auto belt than in the rest of the country (except obviously culturally liberal or minority areas). But this will be hard to tell for a while, without a competitive statewide race in MI or IN.
And I also love the PA trending right phenomenon. I had arguments with supersoulty back in 2004 about this. He was talking about the older Dems dying off out in western PA. He was right, but if anything the older folks dying off in Jack Murthastan actually helps the Democrats in Presidential elections because they were socially conservative racists who were trending Republican anyways.
The only areas I could see are:
Appalachia- SW Pennsylvania/SE Ohio/West Virginia/E Kentucky/Western Virginia
Upper/Outer South- TN, AR, MO, LA, OK
An area I'm familiar with. Not as sharp as the above 2, but I noticed some kinks here. And dare I say.. race maybe an issue, but still:
Blue collar white Northeast Corridor- Northeast/South Philly, Staten Island, Some parts of NJ, Eastern MA (interesting trends here. If Bill Delahunt/Steve Lynch were to retire..), Parts of Rhode Island.