The DNC chairman warns that Clinton-Obama sniping may "demoralize the base of the Democratic party."
In wide-ranging interview, says he hopes nominee is chosen soon after voting ends in June, also wants superdelegates to make their choices before the convention.
Plus: Dean says on CNN's "American Morning" that he believes Michigan and Florida's delegates will be seated as soon as they reach an agreement with the candidates.
On ABC's "Good Morning America," says it would be "nice" if superdels announced their support by July 1, if not earlier.
