Hypothetically ... Kerry continues to cruise along winning Blue state primaries/caucuses and the occasional red state by 40 plus percent, with Dean picking up delegates with healthy 2nd place showings. Edwards and Clark also keep picking up Southern states and delegates. Eventually Kerry has enough super delegates and primary/caucus wins that he's the apparent nominee. But Edwards, Clark and Dean all stay in. Heck, the more voices attacking Bush, the better.
Then starting in April, Bush/Rove unleash the storm of negative ads and media slurs and push polling on Kerry that only $200 million dollars can buy. By the time July rolls around, the negative attacks have taken their toll and Kerry's poll numbers are sinking lower than they were last fall. Could happened. Negative advertising works.
Do the super delegates withdraw their support? They aren't enough to give someone else the nomination, but they can deny it to Kerry on the first ballot. If they take the nomination from Kerry, who will it be? The chair of our county Democratic Party likes Dean best, but is running as a Kerry delegate because he wants to go to the convention. What are the rules about changing candidates after the first ballot, hypothetically speaking?