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South Africa’s scandal-plagued president, Jacob Zuma, was clinging to power Tuesday despite growing pressure to step down.

Zuma is a member of the African National Congress, the ruling party that has led the country since the end of white minority rule and the election of Nelson Mandela, but was ousted as its leader in December.

Zuma, 75, was due to deliver a state of the union address on Thursday, but the speaker of South Africa's Parliament announced Tuesday that it would be postponed.

The Nelson Mandela Foundation, a nonprofit group that promotes the legacy of South Africa's anti-apartheid leader and first black president, said Zuma must go "sooner rather than later" and warned that any delay could lead to violence.

Protesters chant anti-Jacob Zuma slogans outside the ANC party headquarters in Johannesburg, South Africa, on Monday. Marco Longari / AFP - Getty Images

“Zuma has been in power for almost a decade, during which time his tenure has been marked by an escalation in corruption,” said Pieter Du Toit, a journalist who co-wrote “Enemy of the People: How Jacob Zuma Stole South Africa and How the People Fought Back.”

“After 1994, when South Africa became a democracy, it really was Mandela’s 'rainbow nation' and held up as a model around the world," du Toit added. "It’s now reached a point where that shine has worn off."

Graft allegations have persisted throughout Zuma's almost 9 years in office. In 2016, he was forced to pay back some of the millions in state money he used to upgrade his private residence.

Zuma's links to the Gupta family — whose members include a trio of businessmen accused of using their ties to the president to amass wealth and influence government policy — has drawn criticism from former allies as well as opponents. The Guptas and Zuma deny any wrongdoing.

In a separate case, Zuma's lawyers last week submitted arguments to the government about why he shouldn't be prosecuted for corruption charges tied to an arms deal two decades ago. The charges had been thrown out but a court reinstated them last year.

South African President Jacob Zuma Pieter Bauermeister / AFP - Getty Images file

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Zuma last month agreed to establish an inquiry into "state capture," a South African term for government corruption.

The end of apartheid and the formation of South Africa's first democratic government in 1994 — which was led by Mandela — ushered in an era of hope.

But the country is now beset by high unemployment (27.7 percent) and low economic growth (around 2 percent). One of its largest cities, Cape Town, is likely to run out of water in the next few months.

The next scheduled elections are more than a year away but a no-confidence vote looms in Parliament on Feb. 22.

Waiting in the wings

Calls for Zuma to step down have gathered strength since Deputy President Cyril Ramaphosa succeeded him in December as leader of the ANC, which was the main anti-apartheid movement for decades before becoming the ruling party.

Ramaphosa is a former labor organizer who was instrumental in negotiating the end of apartheid. He is also is believed to have been Mandela’s preferred successor.

Cyril Ramaphosa Siphiwe Sibeko / Reuters

He’s taken a firm stance against corruption and in January appeared at the World Economic Forum in Davos, Switzerland, where he promised that South Africa was entering a "new era" of clean government.

That message was well-received among business leaders and foreign investors, said Daniel Silke, a political economy analyst.

The opposition — as well as some members of his own party — wants Zuma to resign before Thursday's state of the union address.

“The longer Zuma remains in office, the more polarizing he is to South Africa and the ANC,” Silke said.

On Wednesday, the ANC's National Executive Committee plans to meet to discuss the "management of the transition."

"Since Mandela, South Africans have liked the idea of messiah figure coming in and saving them, but the issues in the country are bigger than one man alone can solve.”

Silke added: “It’s causing internal conflict. The party is desperate to unify ASAP so it can regroup and begin the election campaign for next year.”

Zuma has survived several no-confidence votes in the past thanks to loyal ANC lawmakers. But with weakened support in his own party, there’s no guarantee he could survive again.

“It’s never been assumed he would go easily,” said Chris Vandome, a research analyst for Africa with Chatham House, a London-based think tank. “He has information on others in the party and he still has some influence.”

Whenever Zuma leaves office, the next leader of South Africa will have a big job on their hands.

“After nearly 24 years of ANC rule, the government hasn’t fundamentally changed the structure of the South African economy or business environment,” Vandome said.

If Ramaphosa does indeed take the reins, he faces out-size expectations from South Africans as well as foreign leaders and investors.

“There is such huge expectation both internally and from the international community that people are going to have to be patient and understanding,” Vandome said. “Since Mandela, South Africans have liked the idea of messiah figure coming in and saving them, but the issues in the country are bigger than one man alone can solve.”