They may have to move the final vote to Sunday or next week:

A House leader says Democrats haven’t yet lined up enough votes to pass their health care overhaul bill.
Majority Leader Steny Hoyer of Maryland says the vote that House Democrats had scheduled for Saturday could slip to Sunday or early next week.
Hoyer acknowledged to reporters Friday that Democratic leaders don’t yet have the 218 votes needed to pass President Barack Obama’s historic health overhaul initiative.

I guess they’ll have to break out the pork to sweeten the deal. Maybe Obama can offer the red state Democrats a judicial appointment or ambassadorship if they’re worried about angering their constituents.