KINSHASA: As Laurent Kabilaís rebels entered Zaire's second largest city Lubumbashi to the sound of cheering crowds, preparing to move on Kinshasa, ailing Zairian President Mobutu Sese Seko made a feeble attempt to regain the power he held for three decades, ousting the country's new prime minister Etienne Tshisekedi and naming the army chief of staff to head the government. The White House demanded that Mobutu step down and go into exile, effectively ending U.S. support of the African dictator. "Mobutuism is about to become a creature of history," White House press secretary Mike McCurry said. Tshisekedi, an opposition activist whom the president reluctantly appointed just a week ago, was forced into a vehicle and driven away by six soldiers as he arrived to assume the post. A longtime foe of Mobutu, he had been given the post in an effort to stave off Kabila's advancing rebel forces, which already control nearly half of the country. But Tshisekedi's challenges to Mobutu's once unquestionable authority -- ordering a parliament packed with Mobutu's supporters dissolved, annulling the constitution and offering Cabinet posts to representatives of Kabila's army -- proved too much for Mobutu, who is dying of prostate cancer. Even so, Mobutuís move won't make a bit of difference, says TIME's Marguerite Michaels. "Mobutu controls nothing. There really is no government in power in Zaire. The question is what will happen between Kabila and Tshisekedi. Tshisekedi is the only one who can work with Kabila, and we know Kabila will just continue to take ground, moving his forces and working his way to town."