When Republican Senator Olympia Snowe voted yesterday with the Democrats in favor of health care reform - thus defying her Republican brethren, who are united in their determination to do absolutely squat - she basically upheld a venerable Maine tradition.

Way back in 1950, another independent-minded Republican woman from Maine, Senator Margaret Chase Smith, defied her cowed Republican brethren by publicly assailing a Senate colleague, right-wing demagogue Joe McCarthy. (Virtually alone in her party, she warned, "Those of us who shout the loudest about Americanism in making character assassinations are all too frequently those who, by our own words and acts, ignore some of the basic principles of Americanism - the right to hold unpopular beliefs, the right of independent thought.") And 14 years later, in the '64 Republican presidential primaries, Smith defied the party's ascendent conservatives, who were united behind Barry Goldwater, by flying the moderate banner and running for president herself.

But the difference between then and now, of course, is that Smith had plenty of company; in those days, the Republican party was teeming with moderates, especially in the Northeast. Not so anymore. The GOP is now in hock to its conservative wing, where the agenda basically decrees that uninsured Americans should be left to fend for themselves, and that the profit-maximizing insurance companies should remain free - under the tenent of free enterprise - to cancel sick people's coverage and freeze out those who have pre-existing health problems.

As Olympia Snowe wrote six months ago in a newspaper guest column, "being a Republican moderate sometimes feels like being a cast member of Survivor - you are presented with multiple challenges, and you often get the distinct feeling that you're no longer welcome in the tribe."

In a sense, the big news today is not that Snowe voted yes on reform in the Senate Finance Committee, nor that she might endorse the finished reform measure a few weeks hence. In a sense, she's not the story; her nay-saying Republican colleagues are the story. What's really worth noting is that only one Republican senator seems willing to swim with the tide of history and vote for progress.

As she put it yesterday in committtee, "When history calls, history calls. I happen to think that the consequences of inaction dictate the urgency of Congress taking every opportunity to demonstrate its capacity to solve the monumental issues of our time."

If Snowe had served in an earlier era - if, for instance, she had uttered those words in 1964 (when the Senate tackled one of the monumental issues of its time, the Civil Rights Act); or in 1965 (when the Senate answered the call of history and enacted government health care for elderly people, otherwise known as Medicare) - she would have had plenty of company on her side of the aisle.

Care to guess how many Senate Republicans voted yes in 1964 to ensure equal rights for black people in public accomodations? Twenty-seven.

Care to guess how many Senate Republicans voted yes in 1965 to ensure that black people would have equal access to the voting booth? Thirty.

Care to guess how many Senate Republicans voted yes in 1965 to entrust the government with the health of seniors (otherwise known as socialism)? Thirteen.

And the potential '09 tally of GOP Senate supporters for health care reform? One.

That list certainly puts Snowe in perspective. And given the polarized temper of our times, it will be interesting to see whether the Republicans will try to punish her. Snowe has a 70 percent approval rating in independent-minded Maine, so it's not likely that conservatives can gin up a serious primary challenger for her next re-election race, which is three years off anyway.

But if Snowe persists in supporting health care reform, they could retaliate by refusing to seat her as the top Republican on the Senate Commerce Committee. That job will open up when Kay Bailey Hutchinson resigns in a few weeks to run for governor of Texas. Snowe is next in line, in terms of seniority, but a fellow Republican reportedly warned yesterday, "A vote for health care would be something that would weigh on our minds."

Some Americans, in posted comments hither and yon, have lately bemoaned the notion that Margaret Chase Smith's heir seems to have so much power in the health care debate, and, after all, who elected her to run the country? But this leverage stems from the Senate math, from the fact that she is a lonely caucus of one; if the GOP had not suffered what Snowe calls "the shrinking of our ideological confines," she would not be the sole Senate Republican now willing to legislate health reform for the greater good.

In an April '09 appeal for party diversity, and perhaps hoping to defend her own independent spirit, Snowe quoted a passage from Ronald Reagan: "Let us decide that we can disagree among ourselves as Republicans, and tolerate the disagreement." Good luck with that one, senator.