Presuming however that those of a conservative bent are highly unlikely to vote for Obama anyway, what would be interesting is the degree to which pointing out the untruth of various McCain’s campaign claims is likely to motivate conservative voters to vote for him. Sadly, it wouldn’t surprise me if a constant barrage of Obama ads pointing out the untruths in McCain ads actually mobilised the conservative base to rally around their man, and boosted the likelihood of many conservatives turning out to vote accordingly. But of course if such ads had a bigger impact on liberals, independents and moderates than they did on conservatives (something that strikes me as unlikely), they would still be worth running.

Loved this comment from Josh Marshall about this latest bit of patriotic schtick from McCain:

He’s desperate and reckless. This is what it appears to be: political stunt dressed up as vainglorious self-sacrifice. In other words, typical John McCain.

Mr. Letterman said Mr. McCain had said the economy was about to crater which necessitated that he get to Washington right away. Mr. Letterman then suggested that McCain should not be suspending his campaign at all and that he could have sent in the second-string quarterback, his vice presidential running mate, Gov. Sarah Palin of Alaska, to fill in for him. You dont quit, Mr. Letterman said.

After suggesting that Ms. Palin should be prepared to step up and be ready, because the poor guy is getting a little older, Mr. Letterman reconsidered and said of Ms. Palins readiness, Dont get me started.

Even after Mr. Letterman brought out Keith Olbermann, the MSNBC host and vituperative Republican critic as the substitute guest for Mr. McCain, he continued to assail Mr. McCain for the decision to cancel the appearance. His critique reached a high point when he learned that at the very moment Mr. McCain was supposed to be on the couch next to him being interviewed, the senator was at the CBS News center three blocks away in Manhattan, getting ready to be interviewed by the CBS News anchor, Katie Couric.

Mr. Letterman ordered his director to put on a live feed from that location, which showed Mr. McCain getting made up to go on with Ms. Couric. He doesnt seem to be racing to the airport, Mr. Letterman observed.

After listening to some questions from Ms. Couric, Mr. Letterman said, Hey, John, Ive got a question: You need a lift to the airport?

This man wants to be president of the United States?

He has been floundering. Even Rove has been criticising his ads as inaccurate and most of the media have been getting restless about the fact Palin is a protected species and so has very limited media interviews.

My guess is he thought few people would go beyond the headline or soundbite