Like Chait and Cohn, I think Obama's only real option for passing health care should Coakley lose is getting the House to pass the Senate bill and massaging the differences later. Which means that knocking heads together in the House these next few weeks is going to be the most important task of Obama's presidency so far--possibly his entire presidency.
On the plus side, Nancy Pelosi seems to have a reasonably good grip on her caucus. On the minus side, Democrats will need some Blue Dogs, New Dems and other moderates to pass health care, and these are the people most certain to freak out if Coakley loses.
Then there's this from a recent Politico story on White House chief of staff Rahm Emanuel, who will obviously be central to the effort:
Emanuel is still popular in the House and commands the loyalty among the dozens of Democrats he helped elect in 2006 and 2008 at the DCCC helm. Yet he’s also lost some ground with his former charges, after months of hammering them to support the cap-and-trade bill and other politically iffy initiatives.