There is a difference between the progressive left as the vanguard of the movements for social change, and the progressive mainstream, which follows them along eventually.

The no-nukes movement is a classic example of this. The anti-nuclear energy movement had been making great strides prior to TMI. Now, there hasn't been any new nuclear energy facilities brought online (except those few that were in the pipeline at the time of TMI) since the accident.

Civil rights movement, lesbian and gay rights movement, etc same thing.

I'm not too worried about being part of the vanguard of the progressive left. It's where I've spent my adult life. It is silly to suggest that because the vanguard is behaving like the vanguard, that we are lock-step ideologues. We aren't professional politicians, is all, so we don't compromise nearly as much as they do. If there wasn't a vanguard to hold the mainstream's feet to the fire, nothing would ever change. Sort of like it's been since 1980.