- Secret ballot raises chances Zuma could be ousted
- Zuma's entire cabinet would be ousted if vote succeeds
- President has survived eight no-confidence votes
- Protests planned in capital and Cape Town
Protesters blocked roads with burning tyres and rocks on Tuesday in a show of opposition to President Jacob Zuma hours before the South African parliament was due to vote on a no-confidence motion which could force him to step down.
Newspaper headlines reflected the high stakes at play -- "JZ's moment of truth" read The Star, while The Sowetan declared: "High Noon for Zuma".
Zuma, who has held power since 2009, has struggled to fend off opposition accusations of corruption and mismanaging the economy. If parliament votes in favour of the no-confidence motion, he and his entire cabinet would have to step down.
The parliamentary speaker on Monday ruled the vote would be a secret ballot -- a decision the opposition hopes will embolden members of the ruling African National Congress (ANC) to vote against Zuma.
It was unclear, however, which way the vote would go. The ANC has 249 seats in the 400-seat parliament and the opposition controls 151 seats, so it would take 50 ANC lawmakers backing the opposition to vote Zuma and his cabinet out.
Markets had welcomed Speaker Baleka Mbete's decision, with the rand, bonds and banking shares surging after Mbete's announcement, buoyed by the prospect of Zuma's removal. On Tuesday, the rand traded flat as markets waited anxiously.
In the past year, Zuma has upset investors, in particular by removing finance minister Pravin Gordhan in March. The country's credit rating has been downgraded to junk by two of the top three credit rating agencies, unemployment is at a 14-year high of 27.7 percent and the economy is back in recession.
Zuma has also faced a welter of corruption accusations, which he denies, and the ANC, which has governed since the end of apartheid in 1994, is deeply divided.
"Jacob Zuma has brought our nation to its knees," the main opposition Democratic Alliance (DA) party, which brought the motion to parliament, said in a statement urging lawmakers to vote the president out.
Across Gauteng province, where the commercial hub Johannesburg and capital Pretoria are located, protesters blocked major roads with burning tyres and rocks.
Many clad DA colours carried posters saying "Fire Zuma." Other posters featured a cartoon of Zuma in a dustbin.
Opposition parties also planned a march in Cape Town, where parliament is located, to push for Zuma's removal. ANC party members are also expected to rally in the city to support Zuma.
The leftist Economic Freedom Fighters party was expected to hold a protest in Pretoria.
Zuma's tenure as South Africa's president is due to run until 2019, when national elections will be held.
He has survived eight no-confidence votes during his eight years in power thanks to loyal voting by ANC lawmakers, who form a strong parliamentary majority. But those votes were not secret.
"This motion, just like others before it, will be defeated," a statement from the ANC's chief whip Jackson Mthembu said.
But ANC lawmakers appeared divided.
Derek Hanekom, who was removed as tourism minister in the cabinet reshuffle that cost Gordhan his job, said on Twitter that lawmakers must vote against "massive looting and corruption. Vote for change".
Nomura analyst Peter Attard Montalto said the decision to have a secret ballot was "a significant surprise" but he expected Zuma to survive.
"We still expect the vote to fail, but attach a 30 percent chance of success," he said.
If the motion is successful, Zuma would be removed as state president but would remain as ANC leader until December, when he is due to step down and a new leader elected in his place.
Should he be forced to quit as South Africa's president, the speaker takes over and the National Assembly is expected to elect a new national leader within 30 days.
As the largest party in parliament, the ANC would be expected to select the new president and government.
The ANC -- once all-powerful as heir of South Africa's anti-apartheid struggle -- has lost popularity under Zuma, underscored by its worst electoral showing in over two decades of power in local elections last year. Thousands of people took part in protest marches in April calling for Zuma to step down.