The vote, he said, was “not against the A.N.C.” but against its leader, whom Mr. Malema called “the most corrupt individual in this country.”

Mangosuthu Buthelezi, 88, a veteran of the struggle to topple apartheid and the leader of the Inkatha Freedom Party, said that the “poisoned seed of corruption” had been planted well before South Africa’s transition to democracy, but that misrule by Mr. Zuma had “reached the point that the unthinkable became possible.”

Under Mr. Zuma, he said, the country was for sale “to the highest bidder.”

He added: “This motion of no confidence is not against the A.N.C. We are not here to say ‘A.N.C. must fall.’ It is against corruption, it is against state capture, it is against one man.”

Nhlanhlakayise Moses Khubisa, the leader of the tiny National Freedom Party, said fundamental problems like poverty and unemployment as well as inadequate electricity, water and roads plagued South Africans and their economy. “Economic resources keep shrinking and our economy is not growing,” he said, “thus resulting in huge job losses and relegating the majority of South Africans to utter despair.”

Pieter Groenewald, the leader of Freedom Front Plus, a party of white Afrikaners, urged members of the A.N.C. to abstain rather than vote against the resolution, warning that if they kept Mr. Zuma, voters would blame them, not just the president.

South Africa’s unemployment rate is 27.4 percent and rising. Living conditions have improved since the demise of apartheid in 1994, but the gains have slowed. Public debt is rising, and experts say the country needs to restructure inefficient state-owned enterprises.

Municipal elections last year delivered a major blow to the A.N.C.’s control of Johannesburg and several other cities. After Mr. Zuma summarily dismissed a finance minister considered a bulwark against corruption in March, ratings agencies downgraded the country’s debt to junk status.