The Republican party has a grassroots vs. establishment dynamic going on. The Democratic party has no such thing. In the Democratic party the elders decide who's going to run in the primaries and they body out any challengers -- "wait your turn" they get told, and then they do. I'm not talking about presidential elections or even congressional ones. I'm talking about local politics. If you're an outside and you want to run for office you have a much better chance on the R side than the D side.