The dumb smart and electable ones.
Riiiiiiight, LOL.
I think style will be more important than substance. I don't think Sanders took as many votes as he did from Clinton just because of his views; enough people saw him as more authentic and didn't see Hillary as sufficiently populist for a Democrat. Someone more "a clock turn more conservative" than Clinton can obviously win the nomination and the general election quite easily, but they will need to convince the American people that the Democratic Party is the party that is looking out "for people like them."
