UPDATE (3:21 PM): Per Jonathan Cohn, Steny Hoyer says "clearly we believe we have the votes" and per Josh Kraushaar, Chris Carney (PA-10) will now vote for the bill. Everything looks to be back on track. The Intrade contract -- now at 85 percent -- might in fact be a little cheap.
UPDATE (2:57 PM): Things look to be stabilizing a hair for the Democrats as the caucus made a smart decision not to use the "deem-and-pass" strategy to cast their health care votes, as pro-choice Democrats appear to be comfortable with the idea that Obama will issue an Executive Order on the abortion language (although it's unclear how many Stupak votes this will persuade) and as debates over Medicare spending levels appear to be resolved. I'd say odds for passage are up over 80 percent again -- but obviously this changes on an hour-to-hour and even minute-to-minute basis.
ORIGINAL POST (1:49 PM): As of about 5 PM yesterday afternoon, it appeared that the Democrats were well on their way to securing enough votes to pass health care reform. They had gotten commitments to vote yes from seven legislators -- Betsy Markey, John Boccieri, Alan Boyd, Bart Gordon, Susan Kosmas, Dennis Kucinich, and Scott Murphy -- who had voted no originally and most of whom (with the exception of Kucinich and the retiring Gordon) are in tough districts in which their switching their vote represents a significant political risk. It seemed highly unlikely that those Democrats would be willing to switch unless they were quite confident that the bill would pass -- since switching making a public commitment to switch from no to yes becomes an even larger risk for them in the world in which the reform effort nevertheless fails.
However, with 7 no-to-yes switches, the Democrats can afford at most 8 yes-to-no switches in order to retain the votes to pass their bill. And right now, Chris Bowers puts the number at 10 instead: the 8 most solid members of the Stupak block (Cao, Carney, Costello, Donnelly, Driehaus, Lipinski, Rahall, Stupak) and two (Arcuri and Lynch) who are prepared to vote against the bill for non-Stupak reasons (although Lynch is pro-life). Some people also put Marion Berry (Arkansas) in the Stupak group; I'm not sold on that that since Berry voted for the reconciliation bill in committee ("undecided" seems like a more appropriate tag).
Still, Pelosi has several ways to get to 216.
1) Convince the other two retiring Dems (Baird, Tanner) to flip and hold everyone else. It's surprising, given how many Democrats in tough districts have agreed to switch, that the retiring Brian Baird and John Tanner haven't, especially since Baird is fairly liberal. But neither has ruled out voting for the bill. The trick, of course, is that if someone is retiring, you don't really have that much leverage over them -- although things like Ambassadorships can sometimes be promised. In any event, these are the two "easy" renaming no-to-yes flips; there are maybe one or two other members that Pelosi could call on in a pinch, but most of the universe of potential no-to-yesses have either committed to voting for the bill or voting against it.
2) Pick off Lynch and Arcuri and hold everyone else. These are the two yes-to-no defectees who aren't members of the Stupak block. Both have resisted repeated calls to reconsider -- but the Democrats have the opportunity to play hardball with each, as Lynch could lose his committee and leadership positions and as Arcuri could be quite vulnerable to a primary challenge.
3) Pick off individual members of the Stupak block (and hold everyone else). The fact is that the Stupak block has never been totally solid, fluctuating between as few as 5 or 6 members and as many as 12 or 13. The statements that various members of the group have made about the bill involve varying degrees of equivocation. Someone like Carney, for instance, or perhaps a Driehaus, could still possibly be picked off. This may be one thing that Pelosi is trying to do by declaring that a Stupak deal is off the table -- a Carney has no incentive to compromise if he thinks that Pelosi will just cut a deal with Stupak anyway.
4) Cut a deal with Stupak after all. Risk-reward: you could get the yes votes as high as 220-223 (possibly including a Republican, Joseph Cao) -- or you could see massive defections among pro-choice Democrats and the whole thing collapse. Although Pelosi might claim that a deal with Stupak is off the table, it seems unlikely that it wouldn't revisit it if it's her only renaming option. (EDIT: There also appears to be an option #4b -- which is some sort of clarifying language on abortion via Executive Order.)
Obviously, none of these paths (except #4 to a large extent) are mutually exclusive -- nor are they necessarily sufficient if other undecideds and lean-yes votes (who have a number of unrelated objections) decide to complicate things for Pelosi. Still, the fact that there are several potential paths to 216 mean that the odds remain in the Democrats favor. On the other hand, the number of options also complicates things in another sense, since Democrats who might want to see the bill pass but don't want to vote for it might not be convinced that their no votes would in fact doom the bill.
You can also read Pelosi's statement that a Stupak deal is off the table in various ways: it could indicate strength (that she thinks she can get to 216 without him), or that such a compromise would be untenable to too many pro-choice Democrats, meaning that one of Pelosi's options is off the table.
The downgrade in the chances of passage at Intrade (to about an 80 percent chance of passage at this writing versus the high 80s yesterday evening) clearly seems warranted (I might go closer to 75 percent myself). Fundamentally, however, it seems likely to me that Pelosi has at least 216 members potentially willing to vote for the bill if their vote makes the difference between passage and failure -- even without brokering a deal with Stupak. That she has 216 potential yes votes, however, doesn't mean she'll actually get them. This is a very complicated bargaining process. The greatest risk, perhaps, is that the negotiations start to break down on multiple levels -- i.e. she's having headaches with some members over Stupak, with others over deem-and-pass, with still others (like Pete DeFazio) over Medicaid equity, etc. If that happens, there could be a sort of "run on the bank" as wavering Democrats seek to distance themselves from the legislation. In particular, if some seemingly solid (but electorally vulnerable) yes votes start to equivocate -- particularly no-to-yes flips that Pelosi previously seemed to have in the bag -- that would be a sign of trouble.