South Africa's opposition derided President Jacob Zuma as a "broken and corrupt" leader Tuesday as lawmakers prepared to vote in a secret ballot that could oust him from office after years of scandals.
Zuma faces a no-confidence vote in the Cape Town parliament later Tuesday in a severe test of the unity of the ANC party that has ruled since the end of apartheid rule in 1994.
"Since the dawn of our democracy, the stakes have never been higher," Mmusi Maimane, leader of the main opposition Democratic Alliance party, told lawmakers.
"Our choice is between right and wrong, between good and evil. Vote with your conscience, and remove this corrupt and broken president from office."
Criticism of Zuma from within the African National Congress (ANC) has grown amid multiple corruption scandals and mounting economic woes, and the celebrated party of Nelson Mandela has declined sharply at the polls.
But senior ANC leaders and most analysts believe the president will survive the vote given the party's large parliamentary majority.
"We are not sell-outs... we will vote for the ANC. The ANC rejects this motion with the contempt it deserves," deputy chief whip Doris Dlakude said in reply to Maimane's attack.
Several opposition parties led thousands of anti-Zuma protesters outside the national assembly, while supporters of the president held a rival march.
Zuma, who has built up a network of loyalists in the ANC since coming to power in 2009, has survived several previous parliamentary votes that were held without secret balloting.
A 201-vote majority would be needed to remove him from power, and the ANC holds 249 seats in the 400-seat parliament. His cabinet would also be forced to resign.
Baleka Mbete, the speaker of parliament, made a surprise decision Monday to hold the ballot in secret after a campaign by the opposition who hope to encourage ANC members to vote against their leader without fear of intimidation.
"Mbete's decision was made knowing that Zuma will be secure," Darias Jonker, of the New York-based Eurasia political analysis consultancy, said.
"The vast majority of ANC MPs are not willing to risk the stability of the party in order to remove Zuma in this fashion."
Zuma, 75, is due to step down as head of the ANC in December, and as president before the 2019 general election -- lessening pressure for his party to trigger imminent change.
The ANC has acknowledged recent criticism of the party, including the impact of a cabinet reshuffle in March when respected finance minister Pravin Gordhan was replaced with a close Zuma ally.
Gordhan's sacking led to a string of downgrades to South Africa's credit rating as well as causing the rand currency to tumble.
Public support for the ANC, which swept to power under Mandela in the first non-racial elections in 1994, slipped to 55 percent in last year's local polls -- its worst-ever result.
A handful of MPs, including Gordhan, have joined calls from anti-apartheid veterans and trade unions for Zuma to resign, as South Africa endures record unemployment and a recession.
Zuma has been engulfed by corruption allegations while in office.
A court last year found him guilty of violating the constitution after he refused to repay taxpayers' money used to refurbish his private rural house.
He has been accused of being in the sway of the wealthy Gupta business family, allegedly granting them influence over government appointments, contracts and state-owned businesses.
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.
Zuma is seen as favouring his ex-wife, former African Union chief Nkosazana Dlamini-Zuma, to succeed him ahead of Deputy President Cyril Ramaphosa.