Deputy President Kgalema Motlanthe said Thursday he would accept a nomination to run against Zuma, the Los Angeles Times reported.
Zuma has faced much criticism recently for a state-funded $30-million upgrade to his private house at Nkandla, in KwaZulu-Natal, and for his alleged lavish spending habits, observers said.
The winner of the presidency of the ANC will likely be elected president in 2014, analysts say. The ANC has generally won about 60 percent of the vote in recent elections, the BBC reported.
The ANC has a party conference starting Sunday, and is set to vote next week for president of the party.