Delegates from South Africa's ruling African National Congress are voting on the party's top six leadership positions including who will lead the organization in the run-up to the 2014 presidential election.
President Jacob Zuma is facing a challenge by Deputy President Kgalema Motlanthe in Monday's vote for the ANC chairmanship.
Zuma is expected to receive a second mandate to lead the party. Motlanthe, who withdrew from the race to be the party's number two, will likely be replaced by wealthy businessman Cyril Ramaphosa.
Results from the vote are expected late Monday or early Tuesday.
The election comes as South African police announced the arrests of four right-wing extremists suspected of plotting an attack on a conference of the ruling party.
An ANC spokesman Keith Khoza said the party is still waiting for a full report on the arrests, calling the plot a "disturbing matter."
Some information for this report was provided by AFP and Reuters.