How could the bill die? There are basically five ways:
1) There is a 'surprise' conservative vote against cloture.
Technically, speaking, there are not 60 Democrats who have formally stated that they'd vote yes. Or, someone could renege on their promise to vote yes. With Snowe -- and presumably Collins -- apparently poised to vote against the measure, there is no margin for error.
Still, being good Bayesians about all this, it seems likely that we would have heard something if this were the case. After all, announcing one's potential opposition to the bill is a highly profitable enterprise: Ben Nelson, Joe Lieberman, and Mary Landrieu have at various points in the past two weeks leveraged their threats into either significant changes to the bill text (Nelson and especially Lieberman) or significant 'bonuses'/bribes for their states (Landrieu and Nelson). To announce one's opposition now would probably just kill the bill outright, and fail to extract any such concessions. Therefore, this seems unlikely, although it's certainly not impossible. The odds probably improve from 'very unlikely' to merely 'unlikely' if the Republicans succeed in delaying the floor vote until after Christmas.
2) There is a 'surprise' liberal vote against cloture.
As Chris Bowers has pointed out, while Democrats like Bernie Sanders and Roland Burris have threatened not to vote for the bill upon final passage, none have yet threatened -- much less pledged -- to vote with the Republicans on a filibuster. Also, the amendments forced by Nelson appear to be somewhat milder than what I had been anticipating, and Reid has also introduced a couple of changes that the liberals should like, such as a ban on lifetime coverage limits. So, although the senators we are dealing with -- particularly Roland Burris -- are somewhat unpredictable, this too seems unlikely.
3) The bill receives 60 votes for cloture, but fewer than 50 for final passage.
We mention this for the sake of completeness, but it seems extremely unlikely as most of the 'veto points' in the Senate, like Nelson and Evan Bayh, have essentially been treating their cloture vote as equivalent to an up-or-down vote. Nor is there enough potential liberal opposition. If Nelson, Lieberman, Bayh, Landrieu, and Lincoln (from the right) and Burris, Sanders and Feingold (from the left) all voted against final passage, that would still leave the bill with two extra votes to spare.
4) The House votes against the conference report.
According to many sources, including the White House in their Thursday conference call, there is still highly likely to be a conference report in order to reconcile the House and Senate versions of the bill -- which of course contain significant differences, including the public option.
This is arguably the most likely avenue for the bill's defeat; the measure, after all, passed the House with only two extra votes, and I'd expect some liberal groups to shift their attention to the House and urge progressives to kill the bill. However, that neglects the fact that some moderate and conservative Democrats who voted against the bill the first time around will probably now vote for the compromise with the Senate, which will be significantly more moderate. It also neglects the fact that Nancy Pelosi is a significantly more skilled vote-whipper than Harry Reid. So, this is perhaps the most interesting thing to watch, but it again seems unlikely that the bill will fail to clear the hurdle.
EDIT/UPDATE: Opposition from pro-life Democrats to the Senate bill's milder abortion language could still be a significant flashpoint.
5) The Senate filibusters the conference report.
Yes, conference reports can be filibustered, although they can't be amended, which reduces the likelihood of brinkmanship gone awry. Once the bill has been reported out of conference
, you can't threaten to vote against cloture in order to extract concessions because you won't get any -- you can simply vote against cloture to kill it.
Of course, it's that qualifier that matters -- once the bill has been reported out of conference
. The fight, to the extent there is one, is liable to take place in the conference committee itself. At the end of the day, though, I figure there are probably a majority of votes in the House for the Senate bill as is -- for every liberal vote that is potentially lost, a Blue Dog vote is potentially gained. And so long as there is that daylight, the Democrats are highly likely to find it. That's not to suggest that there won't be some real issues to be hammered out, or that there isn't some chance of best-laid-plans going awry, but again this isn't a likely outcome.
Overall, the safe and sensible assumption is that the bill is in the 80-90 percent likelihood range for moving to the President's desk and becoming law.