Lincoln Chafee, a Republican-turned-independent, commemorated the impending retirement of fellow Senate legacy admission Evan Bayh with an op-ed reviving the fantasy of a centrist third party:

So I can certainly understand Senator Bayh’s remarkable decision to leave, but I also suspect that he’s not willing to give up on Washington. When he suggested recently that a third party could be a viable contender for the White House in 2012, my first thought was that he was focused on a future as an independent — and the exciting new avenues for public service it offers.

In 2001, John Zogby, the pollster, told our Republican caucus, “There is a burgeoning centrist third party waiting to be formed.” Either party could make a strategic decision to capture the center, he said, or both could wait for a third party to fill the vacuum.

Barack Obama stood in as a kind of third-party candidate in 2008, with an attractive message of hope, change and a post-partisan approach. He captured that popular, centrist energy for the Democrats.

So far, I’m sorry to say, he’s proving my assertion that Republicans lead in the wrong direction and Democrats are unable to lead in any direction at all…

With our hopes for a post-partisan era still unmet, I say to Senator Bayh: Welcome to the club of independents who are looking for a better way to serve. Before long, we centrists may even come together to define the third party that Mr. Zogby foresaw in 2001.

It has happened before. In 1856, my former party ran a credible presidential campaign just two years after its founding. Four years later, Abraham Lincoln won the White House under that new Republican banner. If my friend Evan Bayh can walk away from the United States Senate and not look back, more power to him. But my guess is, he has a modern-day reprise of the Lincoln victory in mind.

What Chafee doesn’t understand — just like Mickey Kaus, Ron Brownstein, Unity ’08, Hotsoup.com, James Fallows, Andrew Sullivan, Sanford Levinson, Dick Morris, Bob Shrum, and many others — is that it’s virtually impossible for a third-party candidate to win the presidency. Here’s what I wrote back in 2005:

To even become a viable contender as a third-party candidate, you have to spend tens of millions of dollars to get on the ballot in most or all states, plus you need to compete in the ad wars and develop your own grassroots infrastructure from scratch. The party candidates can just plug into an established infrastructure that qualifies them for ballots, ensures them millions of loyal voters, and turns them out on Election Day. As a result, the relentless winnowing of Duverger’s Law means they are almost surely going to be one of the two top candidates. It’s certainly possible for a third-party candidate to become one of the top two, but it hasn’t happened since Teddy Roosevelt in 1912 (and he was an ex-president), and a third-party candidate hasn’t won since Abraham Lincoln in 1860.

And even if a third party candidate did well enough to prevent both major party candidates from winning a majority of Electoral College votes, the race would almost certainly be decided in favor of one of the two major party candidates by state delegations in the House of Representatives.

Also, the comparison to Lincoln and the Republicans is specious. The reason that there was an opening for a third party in the pre-civil war period is that slavery was a highly salient issue that cut across the axis of partisan conflict and internally divided the major parties. No comparable issue exists today.