Washington - Now, two people will have to choose. The fate of the health care bill is largely in the hands of Barack Obama and Olympia Snowe.

    The Finance Committee's vote on Tuesday to send its bill to the Senate floor vindicated President Obama's strategy of giving Congress wide latitude to write the early drafts. Major health reform has advanced further than it ever has before.

    But Obama must now abandon his preference for intervening forcefully only after House and Senate bills go to a conference committee. Instead, he needs to focus on the core goals of insuring as many people as possible and expanding, rather than contracting, the choices Americans will have under a new system.

    However policy experts judge the final product, reform will be sustainable only if beleaguered citizens feel more secure, not less, and more confident than they are now that health insurance will be priced within their reach. Obama has said he will own this thing in the end. He's right, and he has to make clear what kind of system he wants to buy.

    So does Olympia Snowe. Against much conventional thinking, she realized that being the only Republican senator to vote for the bill would vastly enhance her ability to shape the outcome. Now that Democrats have gotten their lone Republican vote, they don't want to lose her - in part because Snowe's support will give cover to the more reluctant moderate and conservative Senate Democrats who must vote "yes" if a bill is to get through.

    But what does Snowe really want? It's not clear that even she knows the answer to that question. Many on the left are worried about how she'll use her power. The irony is that it might take a Republican from Maine to advance causes dear to progressives - if she makes those causes her priority.

    One of Snowe's fears about the bill that emerged from Sen. Max Baucus' committee is that it still does not make insurance affordable enough for many in the middle class. She is absolutely right to worry. The subsidies in the bill are too low - held down by Obama's unfortunate insistence that, largely for cosmetic reasons, the final cost had to be held to around $900 billion. For an extra $30 billion or so per year, the bill could put insurance in reach for many more people.

    The subsidy shortage is creating a vicious cycle. It's not fair to impose a mandate on people to buy insurance if doing so will break the family budget. So Snowe and Sen. Charles E. Schumer have moved both to lower the penalties on those who don't buy coverage and to protect more people from the mandate. That's the fair thing to do, except that lower penalties mean more people opting out of insurance. This, in turn, means that more will be uninsured.

    The subsidies have to rise, and if Snowe makes affordability her highest priority, as she has suggested she will, she'll be doing everyone a favor.

    Snowe also has sympathy for Sen. Ron Wyden's desire to give those who already have coverage access to the insurance exchange the bill would establish. Here again, Snowe could do good by helping to expand people's choices.

    She could do the same by showing flexibility on creating a public insurance option. At the moment, Snowe favors only a trigger that would bring the option into being if insurance proved unaffordable for too many. But Schumer, who has emerged from this process as a champion negotiator, has been working with Snowe for months to find a middle ground acceptable both to her and to public option advocates. Much depends on the success of their partnership.

    It's true that Snowe could also make the bill worse, especially if she persists in her opposition to a strong employer mandate. The Finance Committee bill has a bizarre "free rider" provision that would penalize only businesses whose employees get government-subsidized insurance. This creates a perverse incentive for employers not to hire lower-income people, particularly single mothers. A stronger employer mandate is needed to hold the system together, and to provide financing.

    Still, a bill reflecting Snowe's core concerns would be better in most respects than a bill that didn't, and how she chooses to use her influence will owe a great deal to how Obama chooses to influence her. It's another reason why Obama needs to take ownership of a bill that he'll eventually own anyway.

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    E.J. Dionne's e-mail address is ejdionne@washpost.com.

    (c) 2009, Washington Post Writers Group