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with the instant reaction "meter" tracking Reps, Dems and Inds in the audience. Both candidates tanked with Independents (presumeably swing voters) when they went on the attack against each other. McCain tanked deepest when he refused to distinguish Obama's nuance between precondition and preparation with regards to meeting Iran's leadership. The audience seemed to really resent the dishonesty of his argument. His outburst about denying the Holocaust was negatively received as well. Overall, the reation of Independents was more positive for Obama.
While I admit this technique is not scientific, it lends me to believe that the undecided voters (the only ones who count at this point) want to hear facts and reasoned arguments, not attacks.