Mikhail S. Gorbachev moved to take firm control of a watershed Communist Party congress today, fending off a call for his resignation and aggressively defending his reform efforts. The president and party leader seemed to have succeeded in averting a possible challenge to his leadership by hard-liners and the threat of a walkout by radical reformers. ``Voices are being heard that all of our present problems should be blamed on perestroika,'' Gorbachev told the delegates to the 28th Soviet Communist Party Congress in a keynote speech. He acknowledged that the party's top leaders had made mistakes, especially in ethnic relations where ``we did not see the dangers.'' Hundreds of people have been killed in recent waves of ethnic violence in Armenia and Azerbaijan, central Asian cities, and other places. Also, the three Baltic republics are trying to secede. In today's speech, though, Gorbachev laid much blame for the nation's pressing problems _ including the economic crisis _ on the ``heavy legacy'' of previous leaders dating to Josef Stalin. Gorbachev also attacked the Soviet Union's vast bureaucracy, saying many functionaries only cared about protecting their own power and privileges. Radical reform is vital, he insisted, because ``the U.S.S.R. is rapidly becoming a second-rate power.'' He offered few specifics but said Communists must: _``Stop the brain and talent drain abroad.'' _Pass legislation ending the government monopoly on the manufacture of farm machinery ``to provide for an influx of foreign capital in this area.'' _Quickly make the Soviet currency convertible on the world market. _Negotiate a new treaty uniting the 15 Soviet republics on a looser basis while preserving the nation. In the days leading up the party congress, it appeared the Soviet leader might face a challenge from hard-liners for the top party leadership post, and that radical reformers might walk out and split the party. But today, Gorbachev seemed successful in his exhortations for unity among party reformers and moderates. Members of the radical Democratic Platform said they had dropped plans to walk out of the congress to form their own party. Also, hard-liners who last month demanded that Gorbachev give up his post as Communist Party general secretary said they planned to support him, although they might use the new policy of openness to criticize some policies. ``Gorbachev must be the party leader,'' Soviet Premier Nikolai Ryzhkov told reporters at the congress. Public opinion polls indicate the people's trust in the party _ until Gorbachev's tenure the country's sole political force _ has waned significantly as it fails to cope with mounting discontent. Coal miners have threatened a one-day strike for July 11, a day before the scheduled end of the congress, to protest the failure of the Communist leadership to improve living conditions. The nationally televised opening session was tempestuous, in contrast to previous congresses, which were carefully orchestrated by the party leadership. This time, speaker after speaker rose from the floor to offer resolutions and proposals clearly not on Gorbachev's agenda, including a call for the party leadership to resign. Gorbachev, who heads the party as general secretary, did not comment on the demand and the 4,683 delegates approved his proposal to return to the issue later. Conservatives had been threatening for two weeks to try to oust Gorbachev as party chief, but it appeared that threat had diminished. Hard-liner Ivan Polozkov said he would not run against Gorbachev for the top party post. However, Polozkov _ elected last month as leader of the largely conservative Communist Party of the Russian republic _ said he expected Politburo members to explain ``what they see as the way out of the situation that has been created, the loss of direction for which they must answer.'' For the first time, the 12 members of the Politburo are scheduled to report to the congress on their work since the last party congress, in 1986. The progressive Democratic Platform demands that the party give up its cells in the police, military, the KGB and in nearly every workplace. It had authorized its estimated 100 delegates to walk out and form a new party if they are not happy with the session. Such a split would have been the first in the party since 1921. But Sergei Stankevich, a leading reformer from Moscow, said the Democratic Platform leaders had decided against the walkout. Gorbachev, who heads the government as president, wants to use the congress to transform what have traditionally been the most powerful Soviet institutions, rewriting party rules that affect all 19 million party members. The proposed changes include replacing the general secretary with a party chairman and first secretary and renaming and expanding the Politburo, thus diluting the power of each member. Other proposals include nominating multiple candidates for party jobs and restricting elected party officials to two terms. Gorbachev wants to strip the party of involvement in day-to-day administration of the government and economy. He seeks to end the party's domination of government. His most important proposed rule changes would affect the Central Committee, the party's policy-making body and a bastion of conservative holdovers. Politburo member Lev Zaikov has said 90 percent of the 249 Central Committee members should be replaced by younger people. The congress will elect a new Central Committee. Gorbachev had one previous chance to win control of the committee _ at the 1986 congress _ but had been in office just 11 months and lacked the power.
