Baucus can argue that what he has delivered is as far as moderates in the Democratic Party are willing to go — and if liberals try to put in an employer mandate, a robust public option or massive new subsidies for coverage, the delicate balance Baucus forged in his committee will splinter.

And with it, Obama’s chances to sign a bill this year — an increasing political need.

Don’t think Obama doesn’t know that. It’s why the White House has bucked liberals for months by declining to say that a public option is a must-have — and there isn’t one in Baucus’s bill.

And then there’s Snowe. If anything, this bill is slightly farther to the left of where she ideally wants it to be, and she made clear her vote Tuesday doesn’t guarantee a yes on the Senate floor.

So how can Obama move left to win a few liberals — at the risk of losing Snowe and his claims of bipartisanship? He probably can’t.