South African lawmakers were set to re-elect Cyril Ramaphosa as the nation's president on Wednesday, two weeks after the ANC returned to power in legislative elections.
MPs from the African National Congress, which won 230 out of 400 seats on May 8, will choose the head of state in the parliament's first post-election sitting.
The ANC won the ballot with 57.5 percent of the vote, its thinnest majority since the end of apartheid.
Lawmakers were sworn in before the maiden session starting at 2.00 pm. (1200 GMT).
The next president will be sworn in on Saturday and name a deputy president and cabinet at the weekend.
Under South Africa's 1996 constitution, electors vote for a party, and the party selects individuals who go to the National Assembly, which then chooses the head of state.
Ramaphosa, 66, is a trade unionist who played a prominent part in the struggle against white minority rule before becoming a successful business after the end of apartheid.
He will be serving his first full five-year term since taking over last year from Jacob Zuma who was forced out over a series of corruption scandals.
Ramaphosa's first test as he starts his new term will be his choice of a cabinet -- a task beset by rival factions within the ANC.
Prospects of a major reshuffle were heightened hours before Ramaphosa's expected return to office, when Deputy President David Mabuza announced he would defer taking his oath as a lawmaker.
In a report, the ANC's integrity commission alleged Mabuza -- the party's No. 2 -- "prejudiced the integrity of the ANC and brought the organisation into disrepute".
His name has repeatedly come up in media reports for corruption and political killings, when he was premier of the eastern Mpumalanga province before becoming vice president last year.
He became the ANC's vice president in December 2017 when Ramaphosa was elected party leader.
"We have accepted and agreed to a request by the deputy president... to postpone his swearing-in," party spokesman Zizi Kodwa said on local TV news channel ENCA.
Kodwa said it was not a given that Mabuza, as the party's vice president, would become the nation's deputy president.
"The fact that he is deputy president of the ANC is not a guarantee or guarantor of a position of the deputy president of the republic," said Kodwa.
Another senior ANC official, outgoing environment minister Nomvula Mokonyane, who has been named in the ongoing judicial inquiry into state corruption, has also pulled out and will not be an MP.
The main opposition Democratic Alliance's chief whip in parliament, John Steenhuisen said the last-minute withdrawal by two senior ANC members is "very clearly a sign that something is afoot in the ANC".
"It is completely bizarre ...and telling the divisions that exist within the governing party are continuing to exist and we are seeing manifestations of the various factions now playing out," said Steenhuisen.