IN lifting economic sanctions against South Africa, President Bush would take a final step in the direction his administration has been moving for weeks.White House press secretary Marlin Fitzwater said July 9 that Bush is "expected to be able to send a determination to Congress soon" on sanctions. Last month Mr. Bush said that of the five original conditions contained in the United States sanctions law only one - release of political prisoners - remained to be complied with by the South African government. The European Commission lifted its sanctions in April, and with African National Congress (ANC) leader Nelson Mandela admitting this week that the effectiveness of sanctions was eroding it was clear that the US government would have to make a move soon. Still, the White House will certainly face bitter opposition to the move from some members of Congress and anti-apartheid groups. Benjamin Hooks, executive director of the National Association for the Advancement of Colored People, immediately blasted the idea of lifting sanctions and said his organization would consider a resolution condemning it. One of the main authors of the original sanctions bill, Rep. Ronald Dellums (D) of California, said in late June that it was still too early to consider repealing sanctions. He complained that the Bush administration was focusing on technical compliance with the law, while the South African government of Frederik de Klerk had yet to meet the "spirit" of full and open political negotiations with the black majority. "We do not believe there has been compliance with the provisions," says Amelia Parker, executive director of the Congressional Black Caucus. Congress voted to impose US economic sanctions against South Africa in 1986, over a veto by President Reagan. Under the law, sanctions could be lifted by the president after South Africa had: eliminated laws that kept blacks physically separate from whites; repealed the country's state of emergency; allowed once-banned parties such as the ANC back into politics; began no-preconditions negotiations with the black majority; and released all political prisoners. The White House began to seriously review the possibility of lifting sanctions after South Africa repealed its Population Registration Act in June, the law which formed the foundation of apartheid by requiring registration of the races. White House officials said at that point that only the political prisoner provision needed to be met - though critics feel the South African government is still dragging its feet on the no-preconditions talks. The US embassy in South Africa began a study to determine how many such prisoners were still in jail. Anti-apartheid groups estimate upwards of 2,000 political prisoners remain, but the de Klerk government has said many of them were charged with violent acts and should count as common criminals. In deciding to lift sanctions, it appears the Bush administration has accepted this definition of a political prisoner.