With questions still up in the air over whether a group headed by construction magnate Ron Tutor will actually be able to come up with the $675-700 million that it reportedly has offered the Walt Disney Co. to buy Miramax, Disney has demanded that the group make a nonrefundable $40-million down-payment on the deal by Wednesday. Otherwise, it indicated, it will end its exclusive negotiations with Tutor and reopen the bidding to other suitors. At this point the only other suitor on the horizon is a group headed by investor Ron Burkle, who is tied to Miramax founders Bob and Harvey Weinstein. That group had previously bid $600 million but lowered it to $565 million after reevaluating the Miramax library. Asked by the New York Times whether his group intends to make the $40-million deposit, Tutor replied, "You'll know by Wednesday." If it does, it should resolve the question of whether the group will be able to lock up the funds needed to buy Miramax. "Nobody's going to put up that kind of money if there's any doubt," Tutor told the Times .