Zuma last month fired Finance Minister Pravin Gordhan, who coincidentally turned 68 on Wednesday, in a Cabinet reshuffle that intensified concerns about the direction of the country.
He said the police had been told that at least 10000 people were expected to take part in the march. The tools of the worldwide financial system are coming to their rescue, adding pressure to force the government to change course, to keep our leaders in line with the dictates of global capital.
African Independent Congress, African People's Convention, Congress of the People, Democratic Alliance (DA), Economic Freedom Fighters (EFF), Inkatha Freedom Party (IFP) and the United Democratic Movement (UDM) are planning to hold what they call the "National Day of Action" on Wednesday to continue to exert pressure on the president to step down.
South Africa's black president on Monday said many white demonstrators calling for his resignation are racist, in remarks that critics are likely to view as an effort to undercut growing concerns about his leadership.
Zuma said many placards and posters carried by the protesters "displayed beliefs that we thought had been buried in 1994".
Maimane's spokesman Mabine Seabe said of Zuma's comments: "He can not argue based on policy and is trying to distract from the issues by using race as a scapegoat".
The parties said that the march has been granted permission by the authorities.
US regulators aim to keep the ban on in-flight phone calls
Communication satellites and drones have been on the cards as approaches to get the network to beyond reachable areas. No federal regulations now govern Wi-Fi calls during flights, although most USA airlines prohibit all voice calls.
Save SA describes itself as a campaign made up of organisations, civil society groups, business leaders, prominent individuals and South African citizens to keep government leaders accountable to the Constitution.
The march coincides with Zuma's 75th birthday.
The dismissal of Gordhan saw the Fitch and Standard & Poor's agencies cut South Africa's sovereign credit rating to junk status due to fears of political instability and growing corruption. Opposition parties have said that the vote on April 18 could have a chance of success if it is held by secret ballot, but the ruling ANC party, which has a majority in parliament, has said it will vote against the motion.
Zuma says racism is no longer hidden away, like it was in the early years of democracy.
Black people make up 80 percent of the population, yet the lion's share of the economy in terms of ownership of land and companies remains in the hands of white people, who make up about 8 percent of the population.
The march to Union Buildings, the official seat of government, was organised by a coalition of opposition parties following nationwide rallies against Zuma last week.