Voting for the next president of South Africa’s ruling African National Congress party continued through the night and was wrapping up Monday morning, with the new leader of Nelson Mandela’s storied liberation movement expected to be announced later in the day.

The ANC’s new leader is likely to become South Africa’s next president. More than 4,700 ANC delegates have gathered on the outskirts of Johannesburg to vote for a new party leader as President Jacob Zuma’s two terms as head of the party come to an end.

The two presidential candidates are Nkosazana Dlamini-Zuma, former African Union commission chair and Zuma’s ex-wife, and Deputy President Cyril Ramaphosa, a wealthy businessman who has been increasingly critical of the president.

After the conclave got off to a slow start due to disputes over delegate accreditation, voting for the new leadership started late Sunday night and stretched through the night into Monday morning. Overnight, delegates lay on the floor of the conference center and slept slumped in their chairs waiting to cast their ballots.

The race appears to be tight and either candidate could pull off a win, said observers. Ramaphosa had the edge in ANC branch nominations on Sunday, but Dlamini-Zuma’s camp told local media that her supporters had been campaigning hard over the weekend.

Some senior ANC leaders broke with tradition and shared how they voted on social media – an unusual move for a party that prefers to conduct its internal business behind closed doors.

Minister of Police Fikile Mbalula, a Zuma ally, tweeted early Monday morning that he had voted for “mother princess” Dlamini-Zuma, adding the hashtag #womenpower.

ANC National Spokesman Zizi Kodwa and Chief Whip Jackson Mthembu both declared they had voted for Ramaphosa. Mthembu said he cast his ballot for the deputy president “and five other incorruptible leaders” in order to save the party and the country. “We must!!” he wrote.

The ANC’s reputation has taking a beating during Zuma’s scandal-ridden tenure, causing rifts that threaten to split Africa’s oldest liberation party. Keeping the ANC together has been a key talking point at the gathering.

“In all its manifestations, factionalism has become the biggest threat to the organization,” Zuma said in a tepidly received speech at the opening of the conference. “Unity is what will make the ANC and South Africa succeed.” – AP