I often agree with Dave Roberts and I thought this was an interesting piece. I've heard similar assessments of the progressive/liberal coalition before, and I think it's based in truth. I don't think it's necessarily a failure of activists so much as the likely result of a disparate coalition trying to affect often disparate policy changes. It's basically more simple for conservatives; if it's regressive, repressive, or resentful they all support it.
Still, it's probably productive for liberal activists across the spectrum to keep what Dave is saying in mind.
Meanwhile in climate-land, John McCain continues to out-maverick even himself.