This is what I've learned from watching debates over the years:
Partisan Republicans on losing
Our guy would have won, but you cheated and we're voting against you anyway.
Partisan Democrats on losing
Our guy was right, but we know he sucked and we're voting against you anyway.
Undecideds
We like to vote for who ever appears stronger because we can't be bothered to figure it out the truth.
Message to Barack: You need to kick some ass if you want to win because the undecided aren't hearing the message.