Someone in John McCain's campagin has apparently told the Republican nominee that a winning strategy would be for him to repeat ad infinitum that Obama "just doesn't understand."
Whatever the occasion (Townhall Meeting, Interview), McCain repeats this attack line over and over (It's quite funny because it makes him seem so desperate).
The Obama camapaign should make a series of ads commencing with McCain saying "He just doesn't understand about four or five times" and then show him making one of his many gaffes.  The choice in unlimited: Iraq-Pakistan border; Putin President of Germany, etc., etc.