The ANC has begun counting ballots to determine who will lead the party which has ruled South Africa since the end of apartheid but is tarnished by scandals and allegations of corruption.
The delegates started voting early on Monday to elect a leader to succeed Zuma as head of a party.
A total of 4,776 delegates were eligible to cast their ballots in a vote.
After procedural delays that held up the start of balloting, the contest remained too close to call. Most grassroots delegates backed Deputy President Cyril Ramaphosa, while Zuma’s preferred candidate, his ex-wife Dlamini-Zuma,came second.
Ramaphosa has vowed to fight corruption and revitalise the economy, a message hailed by foreign investors while Dlamini-Zuma has pledged to tackle the racial inequality that has persisted since the end of white-minority rule.
Whoever emerges at the helm of the ANC is likely to become the country’s next president after elections in 2019.