Megan McArdle:

Back during health care, I argued that probably borderline Democrats should tell the party to go to hell, and vote in a way that was more likely please their constituents.  No, seasoned political commentators told me, it doesn’t work that way; voting against the party means no support in November.

Well, so does voting for the party, it seems; facing massive losses, the Democrats are looking at a triage strategy.  Borderline candidates may end up bogged down with an unpopular vote, and limited party support in the upcoming midterms.