Politics have become too national in my opinion. The congresswoman is supposed to represent the wants and values of the people in her district. Not that of the entire nation.

The mayor represents just his city, not the nation. Actually now that I think of it, why the hell are the mayoral candidate's abortion views even an issue? That's not even a local issue.

Anyway, there are some districts that won't tolerate full on Sanders/Warren progressivism. But they will tolerate an economic progressive + moderate social views.
The purity folks will say that's not good enough and refuse to put their support behind such a candidate who has a chance to win and vote the progressive line 70% of the time.