Oklahoma Democrats are also an entirely different breed than national Democrats. Remember Rep. David Boren? He was utterly sane and far more conservative than your average northeast Republican. He only lost because he refused to switch parties like so many other southern Democrats did.
That could be said of a lot of state parties... in the past. The state parties have largely realigned to the national one’s Communist ideology. You may have a few legislators that buck the national trend, but they are few and far between.