The runoff to end all runoffs?

Five Thirty Eight points out something intriguing that I hadn't realized about the crucial U.S. Senate race in Georgia between Republican incumbent Saxby Chambliss and Democratic challenger Jim Martin:

A run-off will occur in December if neither candidate achieves a 50 percent majority (a distinct possibility as Libertarian Allan Buckley is likely to draw somewhere between 1 and 4 percent of the vote). It is hard to say which candidate would benefit from a run-off, but the default assumption is probably Saxby Chambliss, who wouldn't have to contend with an Obama turnout surge then, and who might benefit from an appeal to divided government (assuming that Obama wins the Presidency). Then again, in a world where Obama has prevailed, Democratic morale is likely to be much, much higher than Republican morale, and Democratic wallets are likely to be a bit more open; we could easily see eight figures pumped into a run-off election from each side.

Imagine if the Democrats pick up eight seats on November 4, getting them to 59, and the Georgia runoff determines whether they get to a 60-seat, filibuster-proof supermajority. (Or imagine if, perhaps just as crucially, they get to 60 on November 4, and the Georgia runoff determines whether they get to 61, which would give them a Lieberman-proof, filibuster-proof supermajority.) That could be one helluva runoff.

P.S. One factor that increases the odds of a runoff: the Bob Barr effect. Barr, the Libertarian candidate for president, is, of course, a native of Georgia, and presumably he'll do a bit better there than nationally. If so, his candidacy could have some "coattails," causing more votes for down-ballot Libertarian candidates, including the potential Senate spoiler, Buckley. It will be a relatively small effect, but it could be enough to push a close call over the edge into runoff territory.