MOSCOW, JULY 5 -- Soviet President Mikhail Gorbachev and his allies have launched an all-out campaign to reassure Communist Party leaders disgruntled with his rule, and to dissuade them from splintering the party into reformist and conservative factions.

These efforts to keep a lid on the party appeared to be succeeding as delegates to the 28th Communist Party Congress, now in its fourth day, pledged behind the scenes to support the 59-year-old Gorbachev as general secretary, an office he has held for five years.

As the 4,700 party delegates from across the Soviet Union continue to meet, the central question facing the congress is gradually shifting from one of Gorbachev's political survival to what can be done by Soviet Communists to reverse the decline of the country they have ruled for 73 years.

Attacks against the Kremlin leadership mounted further, however, as the congress broke into working groups and went into closed session. There was particularly sharp criticism of the party's social, economic and agricultural policies, according to the official news agency, Tass, and other reports. In one of the day's most caustic speeches, Maj. Gen. Ivan Nikulin assailed the leadership for abandoning the Soviet hold on Eastern Europe, reiterating an increasingly volatile issue among military leaders and party hard-liners.

At the end of a full day of complaints about his handling of domestic problems, Gorbachev summoned more than 300 of the party's district leaders late Wednesday evening and fielded their gripes and questions. The Soviet leader appeared particularly confident and conciliatory throughout, said several officials who attended the session.

Gorbachev, listening to debate until late in the night, also showed an unusual sensitivity to local affairs, delegates said. A party official from Latvia -- one of the three Baltic republics embroiled in a struggle with the Kremlin for independence -- said he complained to Gorbachev that Moscow had confused local leaders by switching its policy on regional issues three times over the course of the year. Gorbachev conceded that an error had been made, the official, Filip Stroganov, said at a news conference today.

Stroganov, who had been opposed to Gorbachev before the meeting, said the Soviet leader had won his support during the session. "I like people with character," Stroganov said. "Yesterday, I saw his character."

Alexander Yakovlev, Gorbachev's staunchest ally in the party's ruling Politburo, also met Wednesday evening with disaffected party members. For three hours, Yakovlev fielded questions from the group of about 100 radical-reformist delegates called Democratic Platform. The radicals are angry about the tone of the congress and have threatened to leave the party if it does not adopt a more democratic platform.

One Democratic Platform delegate said the group was "highly satisfied" with Wednesday night's session but had not yet determined whether it will stage a walkout. The group appealed to Yakovlev to make a bid to replace Gorbachev as general secretary, added the delegate, who asked not to be named. Yakovlev, who indicated during a speech to the congress on Monday that he plans to step down from a senior role in the party, declined the draft.

Conflicts between conservative and radical-reform delegates broke out in nearly all seven working groups, according to Tass and other official reports.

The split in the meeting on ethnic strife in the Soviet Union was typical. In discussing the conflicts that have emerged in the Baltic republics, Central Asia and the Transcaucasus region, Central Committee Secretary Andrei Girenko told the working group that the problem should be blamed on the policies of former Soviet dictator Joseph Stalin. But a "significant part" of the group balked, Tass said, arguing that the current Soviet leaders are responsible.

In a session on international policies, Gen. Nikulin and a number of other military officials condemned the Soviet leadership's foreign policies, including the "unbridled disarmament race" and the loss of allies in Eastern Europe.