But there’s also this: the drop in polls and the recent elections have the Democrats circling the wagons. They are tending to band together instinctively—the way the Republicans did after 2008. That said, I think good sense will prevail and a few mavericks will emerge to vote with the Republicans. We’ll see.
It's a Prisoner's Dilemma type of games theory situation. If all Democrats band together and pass a health care bill, that might very well minimize their overall losses. They'd paint it as a huge victory, and the mainstream media would amplify that spin. It would solidify their base, and if they did it quickly they could hope that the voters would move on to other concerns by November 2010.
However, there will be individual Congressmen and Senators who will be adversely affected far beyond the party average. If those individuals manage to kill it now, their survival chances will be higher than if they go along with the herd, or if they wait till later and are accused of playing it both ways (remember how well Kerry's "I voted for it before I voted against it" went over).
Since any one Democratic Senator can kill the bill, they all have to worry about who else might defect and leave them hung out to dry by voting for a losing cause. If one Senator defects, it's to the advantage of others to do likewise, since then no individual can be accused of being entirely responsible for the bill's defeat. Self interest and the uncertainty of what other Senators may do will thus make unity difficult to maintain.