Somewhere, the ghost of Lyndon B. Johnson is smiling. Senator Olympia Snowe's lone Republican vote for health-care reform in the Senate Finance Committee didn't just advance an issue close to LBJ's heart as President, the Texan signed Medicare into law it was also a masterstroke in political leverage. And no one loved Senate politics more than he. Snowe's yea earned her a member of a weakened minority, from the lovely but not very influential state of Maine a voice in the small group hashing out the final version of the bill. In the Senate, she is just one among 100. But on probably the biggest bill of the century, she's now one of a handful cutting the deal. When the Clinton Administration attempted to pass health-care reform, Finance was its graveyard. This time, the idea survived the committee with unified Democratic support and a veneer of bipartisanship. It's a major step but far from the final one. "My vote today is my vote today," Snowe said. "It doesn't forecast" what she might do down the road. In politics, as LBJ knew, the power of yes is meaningless unless twinned with the menace of no.