President Bush handed Soviet President Mikhail Gorbachev his principal economic objective at the summit with a stroke of a pen last night, signing a U.S.-Soviet trade agreement that ends nearly 50 years of commercial cold war between the superpowers.

The agreement is a key symbolic factor in Gorbachev's program to bring the Soviet Union into the mainstream of the Western economic system, paving the way for the eventual end of U.S. tariff barriers that raise the price of vodka, furs, caviar, petroleum and other products that Moscow wants to sell in the United States.

But granting the Soviet Union equal tariff treatment with other nations in the United States, the so-called most favored nations (MFN) status, depends on congressional approval of the trade agreement and a Bush waiver of a 1974 law that links trade privileges to Jewish emigration from the Soviet Union. Congress has threatened to hold up the trade agreement until Moscow ends economic sanctions against the breakaway republic of Lithuania.

"Short term, it's hard to see a major impact on trade {from the agreement} because the Soviets don't have much to sell us," said Deputy U.S. Trade Representative Julius L. Katz, who negotiated the agreement. "But in the long term, there are opportunities to develop trade."

U.S.-Soviet trade amounted to a minuscule $5 billion last year, largely in grain sales to the Soviet Union that left the United States with a $3.5 billion surplus.

Gorbachev got an earful of congressional ire from House and Senate leaders yesterday morning during a meeting at the Soviet Embassy. Both the Democratic and Republican leaders of the Senate, George J. Mitchell (D-Maine) and Robert J. Dole (R-Kan.), as well as House Majority Leader Richard A. Gephardt (D-Mo.), linked passage of the trade agreement to Lithuania. "We have a political problem, too," said Mitchell. Dole said senators want "some fairly ironclad assurances" that Lithuania will gain independence.

It is unclear whether Bush will send the trade agreement for congressional ratification in the face of such opposition, although administration officials believe he could win a veto fight.

Bush also has said he would not ask Congress for a waiver of the 1974 Jackson-Vanik amendment, which links MFN to Jewish emigration, until the Supreme Soviet passes pending legislation giving citizens free right of entry and exit. Soviet officials accompanying Gorbachev blamed the delay on "bureaucratic foot-dragging" and said there is no political barrier to passage of the legislation, which had been expected here before the summit began.

Despite the congressional opposition, the trade agreement has strong support among American business executives and farmers, and the Soviets played to that by balking at signing a long-term grain agreement, which would put millions of dollars in the pockets of American farmers, until Bush signed the trade pact.

Further, the trade agreement would make it easier for Americans to do business in the Soviet Union, protecting software, machines and blue jeans from piracy and ending discriminatory practices that hamper foreign trade. The Soviets are unlikely to implement those provisions of the trade pact until they get MFN status.

The National Association of Manufacturers urged Bush Wednesday to sign the agreement, saying that U.S. trade policy should advance America's commercial interest and not be used to send a foreign policy message.

"Without some clear indication that the pending U.S.-Soviet trade agreement will be implemented, American business proposals will get short shrift in the Soviet Union compared with those from Europe and Japan," NAM President Jerry Jasinowski wrote Bush.

The administration's economic policy officials -- Treasury Secretary Nicholas F. Brady, U.S. Trade Representative Carla A. Hills, Commerce Secretary Robert A. Mosbacher and Michael J. Boskin, chairman of the President's Council of Economic Advisers -- made an economic case for signing the agreement in a joint memo to Bush. But they noted the president's decision also must consider geopolitical and domestic political aspects.

Granting MFN status would lower the tariffs on a liter bottle of vodka by $1.10. It would slash the tariffs on sable furs to 8 percent from 50 percent and cut tariffs on caviar in half, from 30 percent to 15 percent.