WASHINGTON - U.S. Democratic party chairman Howard Dean says either Hillary Rodham Clinton or Barack Obama must drop out of the presidential race once the primaries end in June.

Dean isn't saying which candidate should concede.

But he tells ABC's Good Morning America that one of them has to go by then in order to unify the party so it can win the election in November.

Democratic party rules allow so-called superdelegates to wait until the party's Aug. 25th convention to make up their minds.

But Dean says that would be too late to unify the party and defeat the presumptive Republican nominee, John McCain.

Obama currently has more delegates and popular votes than Clinton, but she is just coming off a big-state win in Pennsylvania.

Dean, meanwhile, said he won't have to tell either Clinton or Obama when it's time to leave the race.

"Either of these candidates, if it's time for them to go, they'll know it and they will go,'' Dean said. "They don't need any pushing from me. You know when to get in and you know when to get out. That's just part of the deal.''

Dean said that "none of the so-called party elders I talked to'' think the contest should go until the convention. "I agree with that,'' Dean said.

"We've got nine more primaries ... Five hundred of the 800 unpledged delegates have already said who they are for.,'' Dean said on NBC's "Today'' show.

"The remaining 300 will do that by the end of June and we'll know who our nominee is and that's what we need to do,'' he said.