Now that the Senate Finance Committee has voted for the health-care bill drafted by Montana Democratic Sen. Max Baucus, negotiations over the real bill can begin in Senate Majority Leader Harry Reid's cozy Capitol hideaway. It won't be easy.

Democrats now face a central problem for any governing party: How to pass a major piece of legislation when there are a lot of sharply different ideas about what should be in it. Trying to reconcile what Democrats in the House prefer with what Democrats in the Senate want is already opening up divisions among the party's supporters.

This week, for example, leaders of 30 labor unions called for Democrats to reject Mr. Baucus's bill because it doesn't include the government-run health insurance program better known as the public option. This only makes it more likely that Democrats will have a bloody fight over the public option.

Members of Congress have a tendency to take a hard stand on a particular portion of a controversial bill. That allows them to show a little independence and make a plausible claim to have influenced the eventual outcome.

The problem for Mr. Obama is that the Baucus bill is being sold on the strength of accounting tricks that make it appear that it won't add to the deficit. (This is true for the other health-reform bills, too). If fiscally conservative Democrats sign on to the bill now after publicly saying they are doing so because it doesn't add to the deficit, they may end up bailing once the tricks are revealed to the public.