Gorbachev’s Main Goal: Broad Western Support : Soviet Union: He is seeking such a commitment to build critical momentum for his reform program.

More than billions of dollars in low-interest loans, more than shipments of meat and grain, more than sales of advanced Western technology, Soviet President Mikhail S. Gorbachev will be bidding today for a broad Western pledge of support that he can use to build critical momentum for his stalled program of economic reforms.

Gorbachev, who wants to use the power of the world market to pull his country out of its profound crisis, is seeking a commitment from the leaders of the world’s major industrialized democracies to end the Soviet Union’s long economic isolation.

Such a promise, in the Soviet president’s calculations, would provide vital underpinning for his sweeping economic reforms, including the privatization of most state-owned enterprises, the freeing of prices to respond to market forces of supply and demand and a sharp reduction of the government’s huge budget deficit.

“The role the West can play is to accelerate the process of change, to make it broader and bolder, to support this transformation that we are undertaking,” said Vladimir I. Shcherbakov, the first deputy prime minister in charge of economic reform. “The West, if it chooses, can provide a critical margin, a guarantee of success.”

Gorbachev, who arrived in London on Tuesday evening, was greeted by words of encouragement for his country’s further reforms--but also by warnings that Western economic assistance will be very limited.

“There is no chance he will come here and leave empty-handed,” Secretary of State James A. Baker III told a press conference, outlining the West’s readiness to help the Soviet Union integrate itself into the world economy, to convert its vast military industry to civilian production and to develop its energy resources.

But neither the United States nor other members of the Group of Seven are prepared, Baker said, to underwrite Soviet reforms with the massive financial aid that some Soviet and Western economists have proposed.

“If you mean cash grants, he’s not coming here asking for those, and his letter (to the G-7 leaders setting out his program) doesn’t ask for them,” Baker added.

Douglas Hurd, the British foreign secretary, said earlier that the Group of Seven has made it clear in inviting Gorbachev to address the summit--a first for the Soviet leader--that this meeting will not develop a multibillion-dollar assistance program.

Instead, the Group of Seven will hear Gorbachev with sympathy as he outlines his plans for further reforms, Hurd said, and intend to give him a “message of encouragement” for the Soviet people, who are now in the midst of a severe economic crisis with no prospect of rapid improvement.

In their political declaration, the summit leaders said that their “support for the process of fundamental reform in the Soviet Union remains as strong as ever.”

“The scale of this undertaking is enormous: an open and democratic Soviet Union able to play its full part in building stability and trust in the world,” they said. “We reiterate our commitment to working with the Soviet Union to support their efforts to create an open society, a pluralist democracy and a market economy.”

Gorbachev’s appeal for support, however, is the first move in a complex political scenario intended to develop new momentum for his reforms, according to Soviet officials, and the reception he gets from the Group of Seven today is considered a vital element in that scenario.

“We have got to get moving--too much time has been lost already,” commented Vitaly N. Ignatenko, Gorbachev’s press secretary. “We believe that everything is now in place for the next stage of perestroika. Developments over the next few weeks will be vital in the life of our nation.”

Gorbachev is also counting heavily on a treaty with the United States to reduce the superpowers’ strategic arsenals, as well as a Soviet-American summit in Moscow, the signing of an agreement laying a new political foundation for the Soviet Union and the first moves to shift the country to a free-market economy.

“It’s, first of all, psychological--a question of confidence,” said Sergei Grigoriev, who is a former Gorbachev aide. “If the West blesses the program and says we can count on its support for this transformation, it will give us the courage to begin. . . . We have no choice, really, but the Group of Seven could help us get a good start.”

Western assistance remains controversial in the Soviet Union. Conservatives see aid tied by many conditions that would undermine Soviet sovereignty as well as hastening the end of socialism.

If Gorbachev is turned down and returns with little from London, one of his major claims to the Soviet leadership--his ability to deal with the West--will be undercut, and conservatives will be able to contend that the West is really seeking the country’s economic defeat.

U.S. officials made clear, however, that Washington’s support will be, first of all, political and, secondly, technical; large-scale economic assistance is unlikely, even to underwrite making the Soviet ruble convertible into Western currencies, although that is a major goal of the Gorbachev program.

In his letter to the Group of Seven leaders, Gorbachev proposed creation of a fund, perhaps $10 billion to $12 billion, that protects the ruble’s value, ensuring its purchasing power, once it becomes convertible. The fund would stabilize the ruble’s value by making purchases of the Soviet currency in world money markets if its value began to plunge in relation to other currencies.

The United States regards such a program as impracticably costly.

“There’s a consensus view that all of us want to be helpful to the Soviet Union--that’s clearly a widely shared view,” said David C. Mulford, undersecretary of the Treasury for international affairs. “There is agreement in the group and with the Soviet Union that the fundamental issue here is the necessity for economic reform--a comprehensive, credible reform of the Soviet economy to move it in the direction of a market-based economy.”

Mulford said that the Group of Seven will support associate membership for the Soviet Union in the International Monetary Fund and encourage Moscow to apply for full membership, a process that could take two years to negotiate. The Soviet Union would also receive a substantial amount of technical assistance in transforming its economy, he added, but a $10-billion to $12-billion stabilization fund sought by Moscow is judged as “not a wise thing at this stage.”