A reader of Jay Nordlinger's suggests that when Obama tries to tie McCain to Bush in the next debate, McCain should respond, "Say what you will about President Bush, senator, but he is the twice-elected president of the United States and a good and honorable man. I would rather be associated with him than with Billy Ayers, Jeremiah Wright, and Tony Rezko, to begin with." The reader called it a "debate clincher" and "showstopper."
My guess is that such a response would excite people already safely in the McCain camp, but that any undecideds out there would merely hear McCain reaffirming his Bush ties and talking about three people they've barely heard of.