MOSCOW, JUNE 8 -- The Russian republic's Congress of People's Deputies, in a challenge to President Mikhail Gorbachev's authority, gave preliminary approval today to a passage in a draft declaration asserting the primacy of Russian laws over Soviet legislation.

The key clause in a draft Declaration of Sovereignty was passed overwhelmingly by a 544-to-271 vote of Russian deputies. If the entire declaration is approved next week, the primary locus of political power in the Soviet Union could shift from the center to the republics. The Russian federation, with its capital in Moscow, encompasses two-thirds of all Soviet territory and contains more than half of the country's total population.

Gorbachev, in a joint news conference with British Prime Minister Margaret Thatcher, said, "The Russian congress has not passed anything that would contradict the Soviet constitution," and expressed confidence that "the Russian people will not stand for being pushed to pit themselves against other people, for breaking up the union."

The Baltic republics of Lithuania, Latvia and Estonia, which have proclaimed their independence this spring, previously also had declared that their laws superseded Soviet laws on their own territory. But it was unclear how far the Russian deputies were prepared to push their drive for greater sovereignty, or whether they could enforce the supremacy of Russian law against the will of Soviet authorities.

Gorbachev also said he is ready for "normal, business-like relations" with the newly elected Russian president, Boris Yeltsin, as long as his populist rival refrains from "political gambles." Gorbachev's comments on Yeltsin appeared more moderate in tone than at a news conference in Washington Sunday, when he accused Yeltsin of "destructive" political activity.

"We have common goals and tasks," Gorbachev said of Yeltsin today. "The important thing is to have a national consensus to make decisions."

The Soviet leader's remarks today effectively marked his reentry into the increasingly turbulent world of Soviet domestic politics following a week-long respite in North America. His authority recently has been undermined by new crises ranging from ethnic violence in Central Asia to a wave of panic buying in Soviet stores that was triggered by publication of the government's latest economic plan.

But Gorbachev said today that he is determined to push ahead with far-reaching economic reforms despite initial setbacks. He even expressed enthusiasm for the ideas of free market economists such as Milton Friedman, whom he met during his recent visit to the United States.

Gorbachev's meetings with American leaders and businessmen appear to have left him more firmly convinced that the Soviet Union must make the painful transition to a market economy if ordinary Soviets are ever to lead better lives. But he also appeared to have no clear concept of how to achieve his strategic goal beyond an insistence on the need to achieve "national consensus."

The legislatures of Russia, Ukraine and Byelorussia have all expressed varying degrees of opposition to the government's latest package of economic measures, which include a proposal to triple bread prices starting July 1. Today, Gorbachev appeared to distance himself from the government's proposals, criticizing unspecified "drawbacks" and a "mistaken emphasis" on price rises.

In an apparent attempt to encourage Soviet citizens that there is light at the end of the tunnel, the president cited his conversation with Friedman at Stanford University about Japan's economic recovery after World War II. Gorbachev quoted the economist as saying the Japanese appeared then to be completely lacking in energy and initiative, traits characteristic of contemporary Soviet workers.

"Friedman said that a new environment, a new economic climate will have the effect of making people act in a new way. Therefore we must forge ahead, regardless of the initial difficulties," said Gorbachev, in a stunning tribute to a man whom the official Soviet media until recently had dismissed as a right-wing ideologue.

The Soviet leader suggested several areas in which the government's program could be amended and strengthened to create the appropriate conditions for the development of a free market. He specifically mentioned new antitrust legislation, the launching of an efficient banking system and stock exchanges, and new laws on ownership.

Gorbachev's comments suggested that he may be prepared to consider legalizing private property, despite the ideological controversy that this would provoke. Some of the president's closest economic advisers are known to be in favor of the sale of state assets, including land, as a way of encouraging initiative and soaking up the excess supply of rubles in the economy.

Thatcher provided enthusiastic support today for Gorbachev's perestroika reforms, describing them as "the biggest, most exciting, most historic changes that have taken place in Europe for a very long time." Gorbachev later described the Soviet Union as "the center of world politics," saying that "you need perestroika as much as we do."

The talks between the two leaders were dominated by a discussion of the problems posed by German unification, with Thatcher insisting that ways must be found to satisfy Moscow that its security interests are being taken into account. But the British prime minister dismissed a call by Gorbachev for new institutions to provide a link between the North Atlantic Treaty Organization and the Soviet-led Warsaw Pact.