SOWETO, SOUTH AFRICA — WHILE communism is in disrepute worldwide, the South African Communist Party (SACP) could emerge as a powerful voice for millions of black workers when negotiations for a democratic South Africa get under way later this month.A four-day conference of the SACP here saw the party tentatively embrace multipartyism and open membership while clinging to the emblem of the hammer-and-sickle and much of the nomenclature of Marxism-Leninism. Party membership has rocketed from a dedicated band of some 1,500 underground activists two years ago to 23,000 paid-up members of the new legal party. The prospect of the tiny SACP - a staunch ally of the African National Congress (ANC) - getting a new lease on life has been increased by the surprise election last weekend of popular ANC figure Chris Hani as SACP general-secretary to succeed the ailing Joe Slovo, who is also a key figure in the ANC. One of the most remarkable aspects of the conference was that Mr. Slovo and Mr. Hani were defeated in an attempt to remove the term Marxism and Leninism from the constitution and to insert the word "democratic" before socialism in the party program. Nonetheless, they were unanimously reelected by the 400 mainly black delegates. "There was a genuine compromise between the two streams," said Devan Pillay, editor of the authoritative left-wing journal, Work in Progress. "I think the party took a step in the right direction, but I would like to have seen it go further." ANC President Nelson Mandela, who had personally blocked Hani's move to the SACP, gave his reluctant blessing to the move in a telephone call from New York on the first day of the conference on Nov. 5. Hani said he faced irresistible pressure from the party rank-and-file to accept the nomination. He said he would resign his position as a member of the ANC's National Working Committee and probably would be "phased out" as chief-of-staff of the ANC military wing, Umkhonto we Sizwe. IN an interview after the party's first legal conference in 40 years, Hani stressed that the SACP's main objective was to ensure that a radical redistribution of wealth took place in South Africa in an equitable manner. "The problems of this country cannot be solved by a democratic government alone," he said, describing capitalism, and not apartheid, as the "great monster." "The basic issue is the economic empowerment of the black people of this country," he said. In a closing speech to the party conference Sunday, Hani stressed that - while the SACP would uphold the alliance between itself, the ANC, and the Congress of South African Trade Unions (COSATU) - it would also assert its independence. "We intend to assert our own independence as a party," said Hani. "The SACP must be a weapon in the hands of all the working-class people of our country." The exclusion of COSATU from the negotiating process has created tensions in the so-called "tripartite alliance." COSATU Secretary-General Jay Naidoo has made it clear that COSATU will fight to ensure that its political demands are reflected in the ANC agenda. But with Hani at the helm, the SACP could quickly become the negotiating voice for COSATU, which represents more than 1 million organized workers and is less inclined to compromise on issues of principle than the ANC. "It is possible that a political realignment could take place if, for instance, the ANC decides to compromise on the issue of an elected Constituent Assembly to draw up the constitution, and COSATU and the SACP decide that compromise is unacceptable," said Mr. Pillay. Hani said there had not been an occasion so far where the ANC and the SACP had differed fundamentally on a political issue but conceded that there could be differences in the future. "The party is going to be devising its own strategy of negotiations and will have a separate presence at the negotiating table," he said. The SACP, which has lost its closest allies and backers in former East Germany and the Soviet Union, pledged total solidarity with the Communist Party of Cuba and warmly welcomed three guests from the Communist Party of China. President Frederick de Klerk is due to leave South Africa on Friday for a first visit to the Soviet Union and a meeting with Mr. Gorbachev - ahead of ANC President Mandela.