A Bush victory would represent the greatest abdication of responsibility on the part of the electorate in this country's history (I defy anyone to name a worse president who was re-elected, a criterion which rules out Bush's peers in folly like Pierce and Harding). It would confirm once and for all that we are living in a country that is equal to the craziest fantasies of Thomas Pynchon and Terry Southern. Unhinged would be an eminently sane response to such an outcome (though if there's money in it, put me down for Alterman).
I wouldn't bet much on Lapham being the winner. I imagine he, like many of us, will in the face of a Bush win find his capacity for outrage to have been stretched past the breaking point, and will for the rest of his days view American politics with an even more detached bemusement than he does at present. I know I will.
Contrary to the premise of baa's post, most supposedly-liberal pundits will faux-grudgingly admire the naked emperor's new finery, persuading themselves that there is something in the cut of Kerry's suit that makes Bush's naked arse preferable by comparison. Now that would be a bet: which liberal pundit will proffer the most tortured rationalization for a Bush victory? Joe Klein? Richard Cohen? Nick Kristof? No doubt there will be many contenders.
I would say Krugman (to FL's original question), but I don't know that he has any further to go.
Assuming he is able to find a venue (and he probably will), I would nominate the theologian Stanley Hauerwas. In terms of unhingedness, a Christian commentator potentially has a dual advantage: 1) a lack of existential commitment to the present order of things (the belief that the present reality will be radically changed at the end of time) and 2) an independent standard of judgment to employ in that detachment. If Lewis Lapham believes that the American system has failed, he has nowhere else to go, but if a theologian believes the American system has failed, it's not really surprising or really that big a deal in the (very) long run.
I nominate Hauerwas in particular because of his dogged opposition to the Iraq War, as well as virtually everything Bush has ever done. In one humorous incident shortly after the war started, he stood up to preach and asked everyone who supported the Iraq War to stand. Then he went around the room, systematically point at each of them and saying, "Fuck you, fuck you, fuck you...."