But Zuma, 74, retains strong loyalty among many rank-and-file ANC party members, as well as its lawmakers
At least three South African ministers have called for President Jacob Zuma to resign, local media reported Monday, in the most serious challenge to his leadership since he took power in 2009.
The News24 news agency, citing sources in the ruling ANC party, said that Tourism Minister Derek Hanekom, Health Minister Aaron Motsoaledi and Public Works Minister Thulas Nxesi had called on Zuma to step down.
The clash came at a weekend meeting of the African National Congress (ANC) party, which was extended into Monday amid heated debate over Zuma's fate.
The president, who has faced mounting criticism of his leadership, came under further pressure this month when a corruption probe unearthed fresh allegations of misconduct.
The probe by the country's top watchdog investigated possible criminal activity in Zuma's relationship with the Guptas, a business family accused of wielding undue political influence.
But Zuma, 74, retains strong loyalty among many rank-and-file ANC party members, as well as its lawmakers -- easily surviving a vote of no confidence in parliament on November 10.
Increasing numbers of anti-apartheid veterans, ANC activists, trade unions, civil groups and business leaders have called for Zuma to resign in recent months.
"There is no doubt that Zuma is fighting for his political life," analyst Ranjeni Munusamy wrote on the Daily Maverick website on Monday.
"He is hanging on while it is clear that large sections of the ANC and alliance no longer want him as president... The countdown to Zuma's exit has begun."
The ANC, which has ruled since Nelson Mandela won the first post-apartheid elections in 1994, has seen its popularity dive, with local polls in August delivering the party's worst-ever result.
Zuma's term in office ends in 2019, but the ANC is due to elect a new party leader at the end of next year and could decide to replace him as head of state.
South Africa's highest court this year found him guilty of violating the constitution after he refused to repay taxpayers' money used to refurbish his private rural house.
He is also fighting a court order that could reinstate almost 800 corruption charges against him over a multi-billion dollar arms deal in the 1990s.
International credit rating firm Fitch on Friday dropped its outlook for South Africa from stable to negative, pointing to the country's recent political turmoil.
Zuma has also been engulfed by a power struggle with Finance Minister Pravin Gordhan, while economic growth has fallen to 0.5 percent and unemployment hit a 13-year high.
Zuma's loyalists have been at loggerheads with Gordhan, a reformist who is widely respected among international investors.
When Zuma leaves office, the three leading possible successors are his ex-wife African Union chief Nkosazana Dlamini-Zuma, Deputy President Cyril Ramaphosa and ANC treasurer-general Zweli Mkhize.
ANC spokesmen were not immediately available to comment on Monday.