He's pretty liberal, though. I'm not sure "any state" would have elected him had he grown up there. If they did, he'd absolutely have to compromise on a huge number of the positions he takes.
I did say 'almost' any state. Of course it would depend on chance (some really popular incumbent senators of either party he wouldn't have been able to beat since at that time he would be an unknown), but I meant to imply if he ran against someone he had a reasonable chance of defeating. I guess it would help if he had been born sooner, since the early '90's were the last time some of these states voted for a democrat senator (Feingold was elected in '92). The advantage of being an incumbent kind of prevents stating whether or not any of these states will elect a democrat senator again anytime soon.
Most recent map:
Red = 2 republican senators
Purple = 1 Republican, 1 Democrat
Blue = 2 Democrats
Green = 1 Democrat, 1 independent
So let's look at the 'Red' states and see if they've had any democrat senators:
Texas = Before Hutchison was elected in '93, Texas had at least one democrat senator since 1875, so the previous 118 years!
Oklahoma = One democrat senator from '75-'94.
Kentucky = A real mix of parties, last democrat in '99.
Tennessee = From '84-'94 there was 2 democrats.
Alabama = Democrats controlled both seats for 100 years until 1981, then still had one member until 1997. Shelby changed parties, having been elected as a democrat but then switched when the republicans gained the majority in congress in the '90's...wonder if he'll switch back now....
Arizona = One democrat from '77-'95.
Georgia = At least one democrat from the civil war until 2003.
South Carolina = At least one democrat until 2005.
Maine = Last democrat in '95.
States with no democrats since before the 1990's:
Mississippi = Last democrat in '89.
Utah = Last democrat in '77, but they've only got one new senator since '74, so not really a good 'sample size' due to incumbents having an advantage.
Kansas = Ok, you really got me on this one, none since 1939.
Idaho = Last democrat in '81.
Wyoming = Last democrat in '77.
I got these figures from
http://en.wikipedia.org/wiki/List_of_United_States_Senators_from_Maine
and just replacing 'Maine' in the link with whatever state you want (remember to capitalize the first letter!)