South Africa's African National Congress (ANC) is set to vote on who will succeed President Jacob Zuma as its leader, the BBC News reported on Sunday.
The main contenders are the country's deputy president, Cyril Ramaphosa, and former cabinet minister Nkosazana Dlamini-Zuma, President Zuma's ex-wife. The leadership battle has caused fierce political infighting, raising fears the party may split before 2019 elections. Mr Zuma has warned the party is under threat and is at a "crossroads".
The party has been in power since the country transitioned to democracy in 1994 under Nelson Mandela.
More than 5,000 delegates are taking part in the four-day ANC elective conference at the Expo Centre in Johannesburg. The leadership contest is expected to be a close one, with legal challenges a possibility. The ballot is done in secret and a result is expected later on Sunday.
It is expected to be a long day here, after delays caused by arguments over just who is allowed to take part in this key vote. There had been accusations that bogus delegates were accredited, and that real delegates were barred.
This is important because it is likely to be a very close result, whoever wins and the ANC no doubt wants to minimise the chances of the process being marred by accusations that it was rigged.
The issue does now seem to have been resolved, with credentials being presented to delegates. It's expected that the new president could be announced at around 21:00 local time, although it is also possible that time could slip.
President Zuma, who has been in power since 2009, is expected to remain in power until the 2019 national elections. The country limits presidents to two five-year terms.
The 75-year-old has been at the heart of much of the controversy surrounding the ANC party. He currently faces numerous corruption allegations but denies any wrongdoing, having already survived several votes of no confidence in parliament during is presidency.