The plan, under which the F.T.C. would give up antitrust oversight of those industries, was supposed to be announced at a news conference today. But the news conference was postponed and then canceled, with no explanation offered by spokesmen for the Justice Department and the F.T.C.

Other administration officials, speaking on condition of anonymity, said that the overhaul had not been abandoned, but that it would not be announced until after there had been the chance to explain it in detail to members of Congress and to members of the F.T.C. who felt they had not been adequately consulted.

Among those complaining today was Senator Ernest F. Hollings of South Carolina, the Democratic chairman of the Commerce Committee, who said through a spokesman that he had "very substantive concerns" about removing antitrust oversight for several industries from the F.T.C., a bipartisan agency, and giving it to political appointees at the Justice Department.

The F.T.C. is an independent agency, with no political party allowed to hold more than three of the five seats. It was responsible in recent years for antitrust oversight of a number of huge media mergers, including the deal that formed AOL Time Warner (news/quote).

Under current rules, the F.T.C. and the Justice Department share responsibility for antitrust investigations, with the agencies dividing responsibility for individual merger proposals on a case-by-case basis.

Under the new plan, officials said, the Justice Department would take responsibility for all proposed mergers in these industries: cable, publishing, games, television, radio, films, advertising, music and toys. The F.T.C. would take over approval authority for other industries, including health care, oil, natural gas, computer hardware and biotechnology.