"What we are seeing right now is a semi-coordinated, semi-spontaneous revolt on the left to the latest compromises in the Senate health care reform bill. We can talk about the wisdom and possible efficacy of this revolt, but the administration has to deal with the left they have, not the left that they might wish to have (to use some Rumsfeldian logic). What the administration is facing is a consequence of the left having to eat too much shit on a whole host of issues from military commissions, a failure to root out and punish the crimes and practices of the Bush administration, the escalation of the war in Afghanistan, a too-friendly bailout of Wall Street, and now a health care bill that bears little resemblance to what Obama promised us in the campaign.
"Obama can't pass anything that doesn't have unanimous support in the Democratic caucus because of the ruthless obstruction and opposition of the Republican Party. This forces him to govern to the center and make all his compromises with centrist Democrats and/or the two still-existing centrist Republicans in the Senate. The Republican obstruction empowers people like Joe Lieberman. It actually gives veto power to every single senator, but the only way to make up for a defecting Democrat is to win over Olympia Snowe or Susan Collins. So, if Bernie Sanders or Roland Burris revolt, he has to move the bill further to the right in response."
http://www.alternet.org/blogs/peek/144631/why_obama_should_stop_forcing_the_left_to_eat_sh*t/#more