I'm not really clear on what is supposed to be the benefit of all these progressives announcing that unless health care passes they won't be voting for any Democrats. Here's the thing that Democrats just learned in Massachusetts: the base can't save you. In the bluest of blue states, if you run with a progressive agenda and alienate moderates, those alienated moderates will join with the conservatives to kick you out of office. Catering to the base is a losing strategy.
It's all very well to say that they should man up and pass it anyway. This is the sort of thing that sounds very well from the comfort of your living room. But are you prepared to pledge that if health care reform passes, you'll resign your job? Because that's essentially what you're asking them to do.
You might also consider that the voters you're asking them to ignore are their constituents. You know, the majority of the people in their district. The people they ostensibly represent. The people who consistently poll against the various health care plans on the table. Yes, sometimes you should ignore your constituents because time is short and you have information and insight that they don't. But it is not obvious that these bills meet those conditions. Obvious to you, maybe. But not to the rest of us.