Howard Dean was the campaign favorite, and was even setting the stage for Obama in certain ways like with his grassroots fundraising. However "Yaaaaaaw"-Gate took him down. Granted, that was out of context, since the microphones only picked up him and not the crowd, who were as loud as Dean forcing him to raise his voice that loud, but the way it was presented to the public took Dean down.
So what if that is avoided, and Dean goes on to win the nomination in 2004?