MOSCOW, NOV. 17 -- Soviet President Mikhail Gorbachev won overwhelming approval today for a radical restructuring of the Soviet government that will give him complete executive authority, eliminate the post of prime minister held by Nikolai Ryzhkov and increase the powers of the leaders of the country's 15 republics.

Although many details remain vague, Gorbachev's plan -- which stunned the legislature when it was proposed unexpectedly today -- is a fundamental concession to Russian President Boris Yeltsin and others who have called for the formation of a coalition government and the ouster of Ryzhkov, one of the most conservative voices in the leadership.

Gorbachev said he was resolutely opposed to the dissolution of the Soviet Union and said his plan was intended to help form the basis of a renewed union of sovereign states. One of his closest advisers, Georgi Shakhnazarov, said Gorbachev made a quick decision to put forward the proposals after listening to a barrage of criticism Friday at an emergency session of the Soviet legislature.

Ryzhkov said he first learned that Gorbachev would make his proposals 20 minutes before today's session of the legislature, or Supreme Soviet. But by the end of the day, the lawmakers had passed the package by a vote of 316 to 19. It still requires approval by the nation's supreme legislative authority, the Congress of People's Deputies.

Since 1988, executive power in the Soviet Union has been divided between the president and the prime minister, who heads a council of ministers. By conferring overall executive responsibility on the president, the reorganization gives the Soviet Union a system of government more like that of the United States.

If the proposals are adopted, Gorbachev will preside over a cabinet, or Federation Council, composed of the elected leaders of the 15 Soviet republics. Until now, the Federation Council met rarely and had little authority.

Gorbachev said the new cabinet will have the authority to approve or vote down "anything affecting the whole country." Shakhnazarov told reporters that "the last word will be the president's, but most, if not all, decisions will be made on the basis of agreement with the Federation Council."

Gorbachev also proposed measures aimed at easing the Soviet Union's food shortages, reportedly involving increased imports.

The existing presidential advisory council will be dissolved and replaced by a National Security Council, probably made up of the heads of the military, KGB security police, Interior Ministry and Foreign Ministry. Gorbachev also proposed a new body to coordinate government efforts against organized crime and the rampant black-market economy, and he suggested that a vice presidential post might be created to handle some duties that fall to him head of state and Communist Party leader.

As his nation has slid deeper into economic and political chaos, Gorbachev has come under fierce criticism for what have appeared to be indecisive attempts to reconcile radical and conservative proposals to restructure Soviet society. This week, he was compelled to address his critics publicly when the Supreme Soviet called an emergency session to debate the nation's problems. While most legislators called the state of the nation speech Gorbachev delivered Friday rambling and inconclusive, they appeared far more encouraged by today's proposals.

"So long as Gorbachev doesn't go ahead now and make Ryzhkov vice president, we can count today as step forward," said Arkady Murashev, a prominent radical-reform legislator. Another leader of the radicals, historian Yuri Afanasyev, called the proposals "genuine and serious" and said they should help alleviate the chaotic state of decision-making in the country.

Historian Roy Medvedev, a legislator whose views closely reflect Gorbachev's, said: "Ryzhkov looks gone to me. He just has no standing. No one wants him."

Ryzhkov told reporters that he had no idea what his future role would be -- or if he will have one. In a speech today, he bitterly accused Yeltsin of demagoguery and said the Russian president is trying to make Russia "the center of power" in the Soviet Union. Yeltsin and many other radicals have said Ryzhkov, the former head of a huge industrial complex in the Ural Mountains, is incapable of leading the country out of its economic crisis and creating a market system.

After Gorbachev took power in 1985 and began to implement his perestroika reform program, he solidified his authority -- and increased his popularity among supporters of radical reform -- by eliminating conservatives from influential positions and reorganizing the political leadership. But while his new proposal has won at least some applause from his radical critics, Gorbachev's public standing, which is at an all-time low here, is unlikely to rise until people see food returning to stores and order returning to society.

The vacuum of political authority has deepened the economic crisis to the point at which many fear that famine will break out in various regions this winter. Leningrad, for instance, has been forced to ration food for the first time since the Nazis blockaded the city during World War II.

A battle between Moscow and the republics over political and economic power has increased the sense of chaos in the Soviet Union. Presidential decrees are routinely ignored, and economic contracts broken. Legislatures in nearly every republic have issued declarations of independence or sovereignty, and some of them have declared their own laws superior to Soviet law.

Sources close to Gorbachev say that while he is aware that some of the smaller republics -- especially the Baltic states -- are well along the path to complete independence, a new treaty spelling out the future relationship between Moscow and the republics is his only chance to solidify the core of the Soviet Union and to normalize economic and political links throughout the country.

"We cannot embark on this path any further," Gorbachev said today. "We shall not be intimidated by the self-styled freedom fighters for all kinds of sovereignties, claiming the people expressed the will to do so."

Supreme Soviet Chairman Anatoly Lukyanov said the Congress of People's Deputies will vote next month on a proposal that would create referendums to "ask all the people whether or not they want to support a single union."

Leaders of the Baltic republics and Georgia have already made clear that they do not plan to participate in the Federation Council or sign a new treaty of union. Marju Lauristin, an Estonian member of the Supreme Soviet, said the Baltic states intend to negotiate complete independence from Moscow and added that she feared Gorbachev's proposal was inconsistent with democratization.

"It concentrates all power in the economy, in military affairs and in politics in one man's hands," she said.

Armenian President Levon Ter-Petrossian said: "Had Gorbachev thought up this idea of a new union treaty, a new federation, two years ago, he might have saved the day. But now it is impossible."

Ter-Petrossian said, however, that the proposal may help "ease the most important threats we face now in a time of emergency -- the threat of hunger and social rebellion. There needs to be a clear arrangement of power to lift us out of this swamp."

Gorbachev left a number of elements unclear in his speech. Lawmakers were left unsure how the Federation Council and the president would resolve their differences, and many were concerned that Gorbachev was merely trying to put off an even more fundamental redistribution of authority to the republics.

"I hope we're not just talking about changing seating arrangements," said Mikhail Bocharov, a member of both the Soviet and Russian legislatures. "It's too late for all that now."