In the Senate we need the numbers and I can accept but not admire RINOs. I see no reason to rally around ex-Dems like the NYC mayor who isn't much of a better alternative to having a mayor with a D next to his name.
Here in Houston, the mayor's office is a "non-partisan" office. The races are never partisan when the candidates are all D or I. Get one Republican in the race and suddenly it is "partisan". The Republicans who run for mayor down here are conservatives. Even then I am voting for the candidate's politics and not the letter (there is no "gain" for the democrats in saying that they have x number of mayors in major cities in this country; they have no power outside of their cities).
Some Democrats walked away from their party when Clinton embarassed them, but it did not shift the balance of power.