Rival South African opposition parties joined forces on Wednesday when tens of thousand demonstrators marched through the capital Pretoria calling for President Jacob Zuma to resign.
The march to Union Buildings, the official seat of government, was organised on Zuma's 75th birthday and came after nationwide rallies against the president last week.
Zuma's recent sacking of respected finance minister Pravin Gordhan has fanned years of public anger over government corruption scandals, record unemployment and slowing economic growth.
Supporters of the radical leftist Economic Freedom Fighters (EFF), the main opposition Democratic Alliance (DA), and smaller parties mingled at Wednesday's demonstration in a display of unity.
Police said the event had been peaceful.
"You came out in large numbers and sent a strong message," EFF leader Julius Malema told the crowd.
"We are here to defend the future of our children whether you are black (or) white. We are united on the purpose of winning back our beautiful country."
Gordhan's sacking triggered unprecedented criticism from senior figures within the ruling African National Congress (ANC), including from Deputy President Cyril Ramaphosa.
The ANC has since tried to close ranks behind Zuma and has vowed to defeat a no-confidence vote against him in parliament.
The vote is scheduled for next Tuesday but may be delayed due to a legal tussle over whether it should be a secret ballot.
'Moment of crisis'?
"At this moment of crisis, we, as political parties, put our differences aside for one common cause -- to save South Africa from Jacob Zuma," said John Moodey, DA leader in Gauteng province, which includes Pretoria and Johannesburg.
"(Zuma's supporters) will do everything to stay in power, even intimidating MPs. With a secret ballot, we could put Zuma out by a huge majority.
"Even if it doesn't succeed, I can guarantee you that we will have a coalition government in 2019."
Zuma, who came to office in 2009, is due to step down as head of the ANC in December, and as national president ahead of the 2019 general election.
He is seen as favouring his ex-wife, former African Union chief Nkosazana Dlamini-Zuma, to succeed him.
Protesters on Wednesday held placards reading "Zuma must fall", "Hamba tsotsi" ("Go away thief"), and "Zuma liar".
"I came because Zuma has to step down. He sold the country. I don't want him anymore," Mavis Madisha, a 37-year-old EFF supporter, told AFP.
Zuma 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.
The Constitutional Court last year found Zuma guilty of violating the constitution after he refused to repay taxpayers' money used to refurbish his private rural house.
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.
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.
The ANC has lost popularity in recent years and slipped to 55 percent of the vote in last year's local elections -- its worst ever result.
Zuma has easily survived previous parliamentary votes against him due to the ANC's majority.
The president branded last week's protests, which attracted tens of thousands of marchers, as racist.