A big difference between the parties is that most Republicans are happy with their party, and winning is what matters. The Democratic Party is not as homogeneous. There’s a strong contingency that is very unhappy with their party. So, while the Republican hears “let go of your favorite candidate so we can get what we want as a group”, the progressive branch of the Democratic Party hearts “let go of the changes you want so we can elect the guy we want.”
To the center, it sounds like the message is the same, but to the left, it sounds wrong. Party unity can’t be achieved until the vision is shared. The republicans achieved this by going hard to the right. The Democratic leadership think they can keep their base and gain undecided moderates by staying around the center.
As a result, the left keeps feeling left out. The moment that best shows this difference is when during the last convention Sarah Silverman told “Bernie or bust” people they were ridiculous. No one bothered with that call for unity in the Republican side. “Lying Ted”, “small hands”, and all kinds of attacks and low blows are allowed, because in the end they rally around anyone who wins the popularity vote precisely because their agenda is homogeneous.
Democrats don’t have a unified vision, and so they demand the candidate is someone they can love. Unification is not possible. If they want that, they have to make sure all voices are heard. Most likely, a third party will necessarily emerge with a true left wing vision.
