The Mainstream wants hard leftist only and will poo poo any Dem who is Moderate. The Base wants Socialism and so does the Dem Media, And then there is Donald Trump.
Donald forces them left with his irritating Tweets. He calls them out and they can't help but go left. He is preventing them from Pivoting to the middle as is their typical hiding position.
All I can says is "Too D*M Bad"
Nah, they are thin-skinned people who are easy to provoke. The fact that they can be provoked shows how weak they are. Sun Tzu knew quite a bit about provoking your enemy.