This followed court action by the UDM to force Parliament to use a secret ballot after the ANC said its MPs would vote as a block.
Opposition parties said on Sunay they were united in their efforts to ensure that Zuma was forced out of office.
DA leader Mmusi Maimane’s spokesman Mabine Seabe said every effort was being used to get Zuma out. He said a number of marches had been planned for April to send a message to Zuma that he was no longer wanted as president of South Africa.
Cope spokesman Dennis Bloem said the court action by the UDM was one of the available solutions to get Zuma out. He said the planned marches this month would push the ANC and Zuma to think again.
UDM leader Bantu Holomisa said they went to court because they wanted to force Parliament to agree to the secret ballot. He said this was “plan B” for the opposition and they hope the High Court in the Western Cape would rule in their favour.
Speaker Baleka Mbete has said the rules and the constitution did not allow for the secret ballot.
Secretary to the National Assembly Masibulele Xaso said last week that the rules only allowed the secret ballot during the election of the President, Speaker and Deputy Speaker. However, the rules did not allow the secret ballot on other votes.
Holomisa said the court would make a determination on how the matter should be handled.
The opposition has been calling on ANC MPs to vote against Zuma on April 18.
But the ANC decided at its meeting of the National Working Committee last week that its MPs had to toe the party line.