The dynamics working against liberals are fairly obvious: they are the ones who want to help a whole bunch of people in dire straits and nobody else gives a damn. That makes them weaker in the final stages because everyone knows they want it more (that people are desperate) so they will not risk getting nothing at all when so many are suffering. The people who are willing to walk away always have more power in a negotiation.
So, knowing that, why in the hell do they go into every discussion having already given away everything but their bottom line? Especially when the only people with whom they are negotiating are ostensibly on their own team, where presumably the leadership and the president have some extra sway? If there was ever a case for the liberals to go in with guns blazing, demanding repeal of the Hyde Amendment, demanding single payer, demanding huge tax increases on the wealthy, demanding open border access to the health care system (which some countries have.) Then they would have had something to work with.
Instead they went in with the tried and true "don't make trouble" strategy assuring everyone who would listen that they had no intention of upsetting the status quo or causing "distractions" and practically apologizing for even asking for universal coverage. In the end they ended up actually rolling back their position on a matter of fundamental principle. And it sounds like that still isn't going to be enough.
http://digbysblog.blogspot.com/2009/11/goldilocks-was-betrayed-by-digby-all.html