Southern Campbell County. I know this from experience. (Northern Campbell County actually isn't that bad.)
What about Oldham and Bullitt counties? (Both exurban Louisville)
Campbell is probably much worse if you just count the southern half. Obama won Newport, Bellevue, Dayton, Woodlawn, Silver Grove, and possibly Highland Heights, yet Romney still managed to win the county by 23%. How Republican does the southern half have to be for that to happen?
I think Republicans in Oldham County might be a little more like the GOP of 30 years ago. They have money, but I think some of them are a little more wary of the Tea Party.
Campbell County also has that crazy school system.