Assuming success in the Senate (still a pretty big assumption) that bill will have to be merged with the House bill. This is where the fight over the public option is likeliest to boil over. House progressives have insisted that health care legislation include a public option, while Senate centrists seem prepared to kill just such a bill. One of those two factions will likely have to agree to settle. That will be a political decision, and it will be ugly no matter who wins.
Of course, this wouldn't be Congressional politics if there weren't a couple significant caveats to all this: First, the Massachusetts legislature is expected to pass a law allowing Gov. Deval Patrick to appoint a temporary replacement for Ted Kennedy, who died of brain cancer last month. Assuming all goes smoothly and Patrick follows through, Democrats will once again have 60 votes in the Senate. That would significantly change the dynamics of the health care negotiations. In at least a technical sense, Snowe would no longer be necessary to pass a bill: Democrats would be able to do it all on their own, as long as they stayed united against a Republican filibuster. The onus, in other words, would be shifted to conservative Senate Democrats--not Snowe. But they'd still maintain significant leverage.
Secondly, if at some point in this long, involved process, it becomes clear that Democrats don't have 60 votes to overcome a filibuster, then their energies will turn to the filibuster-proof budget reconciliation process. And that would touch off a very different legislative fight.
Got it? Good.