Of course, the Townhall format was not particularly conducive to such controversy. Still, McCain's omission felt odd -- inasmuch as the McCain campaign had frequently referenced Ayers during the runup to the debate.
Presidential candidates typically delegate such attacks to surrogates -- while they stay safely above the fray. In 2004, it was outside groups who performed this function for both sides. Unfortunately for McCain, though, Obama has more money -- and there is no "Swift Boat" cavalry to rescue Republicans this cycle. And time is dwindling. And the economy is the big news. And the media isn't helping him. So McCain finds himself in an unfortunate position: If he wants this attack to have the chance to stick (or even be heard by the masses), he only has one more "event" between now and Election Day in which the eyes and ears of the world will be on him.
And so, it seems reasonable he should put all the cards on the table for this one last debate. Wednesday night is huge.
Of course, going after Obama personally is risky -- and could backfire. In the short-term, voters could punish him for "going negative." But candidates who are down in the polls don't have the luxury of playing it safe. I might also add that stasis is risky; there is a serious danger that if McCain fails to bring up Ayers for a third time, it will be perceived that he has come to terms with the fact that he will not win, and thus, wants to go down "gracefully".
If it is perceived that McCain has decided to cut his losses and go out quietly (in order to keep his reputation with the media intact), his supporters may decide they aren't going out on a limb for a guy who is sawing it off.
Wednesday night may tell us a lot.