The way I'd rephrase that is Obama and the Congressional Democrats chose to take a year and a half to fire one bullet, and that killed the chance to push for a second target. There were legitimate reasons for the strategy, but the shared mistake was in failing to simply get the exact same health care reform done quickly in six months and pronounce it the victory that it was, not just the best compromise they could get through Congress. I agree with Andrew that health care was the key to climate action failing, but there's more to it than that.
I'm making this pronouncement having just bought Eric Pooley's book on this subject, The Climate War. I can proudly say the first three or so pages don't expressly disagree with my thesis. Maybe I'll have more to say when I've finished it.