FOR more than a week, the halls of the Palace of Congresses have rung with the ideological salvos of warring Soviet Communists. Yesterday an angry Mikhail Gorbachev, defiant of his conservative critics, defended his policies of economic reform, his d'etente with the West, and the need for the party to change. ``If some delegates arrived here - and that was obvious at different meetings and during some speeches - in the hope of turning the party back to the past conditions of command and orders, they are deeply mistaken,'' Gorbachev said in a one-hour morning address.
``The policy of perestroika, which aims to renew our society within the framework of socialist choice, is not questioned by this congress,'' he declared.
Despite the visible hostility that interrupted even this speech, Gorbachev 's certain re-election as party leader proved again that he cannot be easily displaced. During Monday's nominations for the post of party General Secretary, numerous delegates admitted, some clearly with regret, that there was ``no alternative'' to his leadership. As the Congress headed into afternoon session, Gorbachev faced only token opposition for re-election as party General Secretary.
Through a combination of intense personal politicking and skillful manipulation, the Soviet leader has managed to preserve a fragile center in the Communist Party of the Soviet Union (CPSU). While the left and right wings of the party are now openly arrayed against each other, neither is prepared to challenge Gorbachev.
``At this moment, it is a victory of the status quo, of the inertia of the party machine,'' comments Andrei Fadin, political editor of the independent weekly Commersant. Developments so far provide Gorbachev with a ``guarantee against a sharp turn to either the left or the right,'' he says.
As the Congress heads to a close, further tests of Gorbachev's strength are expected. The Congress will approve the rules and platform of the party and elect its leadership. With Gorbachev's re-election settled, attention is focused on who will fill a new post of Deputy General Secretary and on the composition of the new Central Committee, which runs the party between congresses.
The Gorbachev leadership seems confident, despite the largely conservative tone from the Congress delegates, that it will win broad approval for reform policies.
``I can divide those who have taken the floor,'' Evgeni Primakov, a member of the Presidential Council, told a small group of reporters. ``Some of them are for the real party as the mechanism of perestroika. Some others want to go back to the time when the party was part of the state apparatus. But I don't believe that historically this second trend has any chance to win.''
The official Tass news agency,dismissed much of the right-wing criticism as ``emotional release'' and ``a lack of political culture.''
The conservatives ``have mounted last-ditch resistance'' to reform of the party, wrote Tass commentator Andrei Orlov, ``because they realize that when a market economy and political pluralism are in place, there will be no room for them.''
Gorbachev fought off a severe challenge from the right on Monday when he won approval of a change in the leadership structure of the party. The delegates voted to include the party chiefs from the 15 republics of the Soviet Union in an expanded Politburo. Analysts believe the decision makes it impossible for the conservative right to control both the highest body in the party and the traditional seat of power in the Soviet Union.
``The expansion of the Politburo membership reduces the influence of strong but isolated rightists or leftists,'' says Fadin. ``It gives Gorbachev a broader field to manuever in, to create combinations, to play one group against another.''
Under the rule changes, the Politburo will consist of the General Secretary, his deputy, the republic party bosses and a small number, likely about five, of senior party officials responsible for specific areas such as ideological work. The current compact group of 12 full members (plus 8 candidate members) will grow to 21-23 full members, Gorbachev said.
Many of the republic party chiefs are traditionally loyal to Gorbachev, such as those from the five Central Asian republics. Gorbachev can claim to represent the principle of equality among the republics as well.
The new deputy leader will play the role of running the party organization on a day to day basis, Prime Minister Nicholai Ryzhkov told reporters at the hall. Mr. Ryzhkov backed the idea of Gorbachev nominating his own deputy, a response to a probable conservative effort to put one of their own in the post.
Gorbachev's success on these crucial party issues is a comeback from last week when he appeared to have yielded to conservative demands that the current Politburo system be retained, one which reflects the party's continued dominance over policymaking in the government.
In large part, Gorbachev and his allies succeeded by old-fashioned lobbying and arm-twisting. They have met repeatedly outside the Congress with different groups, including leaders of grass-roots party organizations, Young Communists and others.
While Gorbachev worked on the conservative stalwarts of the party machine, he sent his liberal deputy, Alexander Yakovlev to persuade the left not to desert the party. ``If the left wing, the democratic wing, were to abandon the party today, it would amount to rendering the worst of services to perestroika, the party and themselves,'' he told a meeting of leftist delegates.