A coalition of church, academic and other groups is organising a protest campaign against Zuma, who apologised after the country's top court ruled that he violated the constitution in a scandal over millions of dollars in state spending on his private home.
The alliance says it will discuss its plans later today.
Prominent South Africans who say Zuma should resign include Trevor Manuel, a former finance minister, and Ahmed Kathrada, a former anti-apartheid activist who was close to Nelson Mandela.