Really? Obama's response was about as good as you're going to get on the fly: "the fact of the matter is that if I occasionally have mistaken your policies for George Bush's policies, it's because on the core economic issues that matter to the American people, on tax policy, on energy policy, on spending priorities, you have been a vigorous supporter of President Bush."
There was an amateur ad put together a couple of months back, contrasting Bush's declining public approval with McCain's rising rate of voting with him. All the Obama campaign needs to do is put a little tag on it, with the clips of McCain and Obama quoted above:
p.s. One thought on "Joe the Plumber." It's true that the original exchange and the post-debate interviews have clearly shown that Mr. Joe Wurzelbacher was and remains very skeptical of Obama's positions and character -- in a post-debate interview he said that Obama did a "tap dance ... almost as good as Sammy Davis, Jr." [corrected] -- but let me ask you this: how many skeptical or critical voters has McCain talked to recently? How often do Democrats get into his Town Hall meetings? Has Palin tried to talk policy with someone who's wavering or leaning the other way?
Also, you can seem more of my post-debate comments here and here.
UPDATE: Joe the Plumber?
Another update: Obama's ad is very like the one I suggested. That was too easy.