If you're watching the debate on CNN, they have a "dial" reaction chart on the bottom of the screen. If the audience likes what the candidate is saying, they dial up and the lines go up. If they don't, they dial down and the numbers tank.
Generally speaking, independents (and obviously Democrats) are registering far more positives for Obama than McCain. Indeed, at certain points, the numbers among indys have taken a nosedive when McCain sets forth Bush's his policy proposals.
McCain's goal in these debates is to win over independents. Without them, he just can't win. Any independent watching McCain repeat Palinized talking points and GOP bluster is unlikely to be won over by this performance.
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Do you think independents are attracted to smirks, snark, and childish insults? (see Exhibit A, indy approval ratings of Palin, Sarah).