The elections - the fifth since apartheid ended in 1994 with Nelson Mandela being elected the country's first Black majority President - will be the first in which "born free" citizens can exercise their franchise.
This will also be the first polls without Mandela, largely revered by the entire country as the Father of the Nation.
Factors cited include great dissatisfaction with issues surrounding Zuma, including the inability of his government to address widespread state corruption, huge unemployment, and poor service delivery. In recent weeks, there were massive violent protests across the country.
The ANC also faces rising opposition in the guise of former members from within its ranks, notably expelled ANC Youth League leader Julius Malema, who has formed his own party, Economic Freedom Fighters (EFF).
Zuma remained upbeat as he announced the keenly anticipated date for the elections. "We are very proud of the manner in which we adhere to constitutional and democratic processes in our country," he said.
"These are historic elections as they take place during the 20th anniversary of our freedom from apartheid bondage. They provide an opportunity for us to further consolidate the democracy and freedom that we worked so hard to achieve, and for which esteemed South Africans such as former President Nelson Mandela sacrificed life's comforts for," Zuma said.
