MOSCOW, JULY 4 -- Soviet Communist Party delegates demonstrated their strong disapproval of President Mikhail Gorbachev's handling of the economy and other domestic issues today as they hissed and booed a speech by the Soviet leader's chief economist defending the introduction of a Western-style market system.

Gorbachev, meanwhile, told reporters during a break in the third session of the 28th Communist Party Congress here that the delegates were really seeking to refine his reform program, not scrap it, and declared that he would resign in two years if he fails by then to improve citizens' lives.

"I think that in two years, if there are no changes, this leadership must go," Gorbachev said in reply to a reporter's question suggesting that time period. The Soviet leader has raised the possibility of his resignation before, but today's statement was his most specific yet in setting a deadline for the success of his reform program.

Gorbachev also denied that his government is interested in clinging to power at all costs, saying that before he began his reform campaign "we had more power." Then he added: "I don't know who had more power than the general secretary {of the Soviet Communist Party}."

"I would like to emphasize," Gorbachev said in impromptu remarks to journalists and congress delegates flocking around him, "that not a single speaker doubted the political course towards perestroika {economic and political restructuring}. It means that the main idea of the congress is how to improve this course."

In response to another reporter's question, Gorbachev said he did not view the party congress as a gathering of conservatives, but as "a concentration not only of Communists, but of the whole society in its present constitution in the country. Therefore, it's about the concerns of the people, about what's happening and the wish to find more correct solutions to solving problems. That is not conservatism."

The Soviet leader made his comments even as many of the 4,700 delegates to the congress were sharpening their criticism of the way the country is being run, and several senior Soviet officials said the strident discontent is certain to result in major changes in the party's ruling 13-member Politburo and policy-making Central Committee.

Already, Alexander Yakovlev and Eduard Shevardnadze, Gorbachev's most loyal supporters on the Politburo, have said they are prepared to step down from party duties and concentrate on their government posts. Yakovlev, regarded as the most reform-minded member of the senior leadership, told the congress Monday that this was his last such meeting.

Shevardnadze said in his address to the Congress Tuesday that he sees no reason to continue both party and government duties. Prime Minister Nicholai Ryzhkov, a leading Politburo member, has also said publicly that he is willing to step down to a lesser party post.

Gorbachev announced Tuesday that three other Politburo members had submitted their resignations -- Nicholai Slyunkov, Vitaly Vorotnikov and Alexandra Biryukova. Biryukova, the only woman in the leadership, was a non-voting member of the executive body. Central Committee Secretary Gumer Usmanov also has resigned.

Although some of the attacks at congress sessions have been made directly against him, Gorbachev is almost certain to hold on to his position as general secretary of the party, delegates have indicated. Even those most critical of his programs have said that there is no viable alternative to replace him.

The resignations in the party leadership come amid strong public disapproval of the Soviet government. Only 8 percent of a sampling of citizens said they believe the current government is capable of moving the country out of its crisis, down from 14 percent a few weeks ago, according to a poll released today by the weekly newspaper Moscow News. In the same poll, only 18.8 percent of respondents said they would vote for the Communist Party if free multi-party elections were held.

The widespread disgruntlement was echoed in today's proceedings of the congress. Called to speak late in the day, Soviet economist Leonid Abalkin, a close adviser to Gorbachev, warned delegates that the socialist ideal had begun to lose its appeal to the Soviet populace and said that the only way to save it was to switch to a market economy. Abalkin also chided those who believe "you can achieve prosperity without sacrifice."

Abalkin, who only narrowly gained approval from the congress to speak, was booed intermittently and at one point delegates began rhythmic clapping to interrupt his speech.

Ayaz Mutalibov, party chief of Azerbaijan, also lashed out at the Soviet leadership for its handling of the ethnic violence between Armenians and Azerbaijanis in the Soviet Transcaucasus. The bloody dispute, which began over a territorial disagreemnt more than three years ago, remains far from settled. Azerbaijanis are particularly bitter about the summoning of Soviet army troops early this year to crush demonstrations in Baku and other areas of Azerbaijan. "History will give due {recognition} to the political course of the man who started the revolutionary perestroika," Mutalibov said, "but contemporaries cannot reconcile themselves with indecision and inconsistency, which may scuttle the cause."

The party chief of Soviet Kazakhstan, Arsultan Nazarbaev, echoed widespread disapproval of the party leadership's treatment of ideology, complaining that the party is now even heaping abuse on Lenin, the founder of Soviet socialism. He was roundly applauded.

Anatoly Poruchikov, director of a state farm in the Soviet Russian republic, complained that farmers are being unfairly treated under the government's economic program. "We are like a big cow for you, you milk us non-stop," he said. "What will happen to you if we all stop?"

In an attempt to forestall even more serious domestic strife, the congress appealed to Soviet coal miners to cancel a nationwide strike they have called for next week, declaring in a resolution that a repetition of last year's prolonged mine walkout would devastate the country's economy.

The miners have demanded nationalization of the vast property holdings of the Communist Party and resignation of the current Soviet government. The strike is scheduled to begin July 11.