Why three parties can't work here

Sometimes, it's actually one of the two national major parties that looks like it's third. In the 23^rd Congressional District of New York State last year, Republican candidate Dede Scozzafava saw herself as third, and essentially withdrew from the election, giving her support to the Democrat in order to defeat a Conservative candidate she abhorred. Perhaps something similar is happening in Florida currently, though in this case a centrist candidate will be the beneficiary. In fact this looks like a mirror image of the election in Connecticut in 2006. When an extreme left-wing candidate, Ned Lamont, won the Democratic primary in Connecticut, Joe Lieberman ran as an independent (well, really as a third-party candidate, but the "party" was a sham created because of Connecticut's ballot access laws) and won, mostly by getting Republicans to abandon their own candidate, Alan Schlesinger, and vote for him to prevent Lamont from winning.

Now fast-forward to 2010 in Florida. Interchange "left" and "right," and also "Democrat" and "Republican." We have the same picture. An extreme right-wing candidate, Marco Rubio, won the Republican primary in Florida. Charlie Crist chose to run as an independent. So will Democrats abandon Kendrick Meek, their candidate, as Republicans abandoned Schlesinger? There does seem to be a possibility! It hasn't happened yet, but people are talking about it. The post I am linking to speaks of Florida black Democrats; since Meek is himself black, this would be a major surprise, but if they really want to prevent Rubio's election, that's about the only way to do it.

Let us see. But this shows why three-party elections don't work well in plurality electoral systems.