ANC delegates attending the party’s 53rd national conference in Mangaung began voting around 02:00 early on Tuesday morning.
Voting was conducted province by province, beginning with KwaZulu-Natal and Gauteng, and ending with Limpopo.
There was only one candidate for the position of deputy secretary general, leaving the positions of president, deputy president, secretary general, national chairman and national treasurer to be decided by the ballot.
Results are expected on Tuesday afternoon when the delegates reconvene in a plenary session after breaking into commissions on Monday night. Counting will take several hours as the votes will be counted manually.
Delegates anxious to vote congregated at the election venue on Monday, waiting for hours for voting to begin after protracted delays.
The electoral commission printed different-coloured ballot papers for the disputed North West and Free State provinces, in anticipation of possible court action which could affect the results.
Supporters of party president Jacob Zuma, who is set to secure a second term as ANC leader, sang throughout the night outside the voting venue as they waited to vote.
Those advocating for leadership change at Mangaung and the removal of Zuma have been deflated by the visible and overwhelming support for the president since the start of the conference, but particularly during the dramatic nominations process on Monday.
Deputy president Kgalema Motlanthe looks set to lose his position on the ANC top six after declining nomination for the position.