I find that there are a lot of electable Democrats in the "Red" states. Here in KY, I have no problem voting for Democrats IF they are the right person for the job.
The issue is just what was said above, the coastal Dems now run the party and they simply just don't like any hick that disagrees with their extremism. Any "practical" politician from the flyover wasteland is only as important to them as the number of votes they bring out of blind party loyalty.
Here in KY, an entrenched Republican encumbent senator was almost knocked off by a conservative Democrat state rep. I think, as a whole, the voters liked the Democrat better but only voted for the Republican just to show their dislike of the national Democrat party. If that dislike wasn't there, I think the Democrat would have spanked the Republican by at least 10 percentage points.