Thousands of supporters of former South African president Jacob Zuma are expected to march to the Durban High Court on Friday, where Zuma will face corruption charges related to a decades-old arms deal.
Zuma plans to legally challenge a decision to prosecute him on 16 charges, including fraud, racketeering, corruption and money laundering, that stem from the $2.5 billion deal.
The case, which is to be heard in Zuma's home province of Kwa-Zulu Natal, is a dramatic development on a continent where leaders rarely face their accusers in court.
Religious organisations and pro-Zuma lobby groups plan a night vigil on Thursday and will march to the court in the morning to protest what they say is a politically motivated witch hunt.
"Could it be that Zuma is targeted because he has always been on the side of the poor," the Commission for Religious Affairs said. "Could it be that Zuma is targeted because he preferred free education for the poor?"
Police expect the march to attract more than 2,000 people and planned to deploy in strength at both the vigil and the march.
"We are to make sure citizens are safe," Kwa-Zulu Natal police spokeswoman Thembeka Mbhele said. "I want to appeal to the marchers to make sure they work hand-in-hand with the police. If anyone commits a crime, they will be arrested."
Zuma was deputy president at the time of the 1990s arms deal, which has cast a shadow over politics in South Africa for years. Schabir Shaikh, his former financial adviser, was found guilty and jailed in 2005 for trying to solicit bribes for Zuma from a French arms company.
Charges were filed against Zuma but then dropped by national prosecutors shortly before he successfully ran for president in 2009.
Since his election nine years ago, his opponents have fought a lengthy legal battle to have the charges reinstated. Zuma countered with his own legal challenges, but prosecutors re-filed the charges after Zuma was forced from power by his own party in February.