About 4,800 delegates of the South African ruling party, the African National Congress, ANC, are expected to elect a new leader to replace President Jacob Zuma on Monday morning as delay caused by dispute over accreditation is being resolved.

On Sunday, the party announced that 400 delegates have been disqualified opening the way for voting to elect the person who will replace Mr. Zuma as the president of the country. The ANC has an overwhelming majority in the country’s parliament and whoever emerges winner of Monday’s poll will ultimately become the country’s next leader.

“This is to ensure credibility of the process,” said ANC’s deputy general secretary, Jessie Duarte, about the disqualifications.

The contest to replace Mr. Zuma, who has been trailed by series of corruption and money-laundering scandals, as the leader of the ANC, is between the country’s vice president, Cyril Ramaphosa (65) and Nkosazana Dlamini-Zuma (68), Mr. Zuma’s ex-wife.

Mr. Ramaphosa, one of South Africa’s richest men, who is preferred by the party’s middle-class and urban dwellers has promised to make the country more attractive to investors and grow the economy.

However, Ms. Dlamini-Zuma, a party veteran and recently chairwoman of the African Union Commission, is backed by most rural voters, women and the youth league who have been her ex-husband’s support base. Ms. Dlamini-Zuma, a medical doctor, is campaigning on the redistribution of wealth from white to black South Africans.

Political pundits say the race is too close to call but some are of the view that with the disqualification of the 400 delegates, and last-minute negotiations on Sunday, Mr. Ramaphosa may be enjoying a narrow lead.

Also boosting Mr. Ramaphosa’s chance is the endorsement by the ANC national chairman, Baleka Mbete. Mrs. Mbete had also been competing to replace Mr. Zuma.

“We have agreed a whole lot more,” she said of negotiation with Mr. Ramaphosa adding that she did not have the opportunity to hold similar discussions with Ms. Dlamini-Zuma.