Johannesburg: South Africa's top court heard arguments from opposition parties on Monday to allow a motion of no confidence against President Jacob Zuma to taken by secret ballot, which they hope could help to depose him.
Ouside the court, around 1,000 protesters from different opposition parties marched peacefully to the Constitutional Court, some waving signs demanding that Zuma be removed.
Zuma and the ruling African National Congress (ANC) have suffered a string of judicial setbacks and the political stakes are high in this case.
The opposition parties believe the motion will have better prospects of toppling the president, who has survived previous such votes, if it is conducted in secret.
Parliament Speaker Baleka Mbete, a top ANC official, has said the rules do not allow for the secret ballot and the ANC chief whip's office has rejected calls for one.
"Our case is very simple. The speaker has the obligation to arrange for a private ballot. We are pleading that she has such an obligation to arrange it and she has failed to do it," Dali Mpofu, a lawyer representing the United Democratic Movement party, told the Constitutional Court in televised proceedings.
A decision was not expected immediately.
The ANC has lost popularity under Zuma, underscored by its worst electoral showing in over two decades of power in local elections last year, in the face of a spate of scandals and a failure to address slow economic growth, high unemployment and glaring income disparities.
Opponents led by the main opposition party Democratic Alliance (DA) believe a recent cabinet reshuffle that led to the dismissal of respected finance minister Pravin Gordhan, triggering damaging ratings downgrades and large street protests, may have angered enough ANC members to desert Zuma.
Some opposition members outside the court said: "No matter what the Constitutional Court decides today - secret ballot or not - all we ask is that members of parliament vote with their conscience," said DA leader Mmusi Maimane.
Separately, local media reported that ANC supporters in the port city of Durban marched to protest against what the party says is the pandering of the judiciary to the opposition.
One of Zuma's recent judicial hitches stems from that decision.
Earlier in May, South Africa's High Court ordered Zuma to provide reasons for Gordhan's sacking. Zuma last week requested legal permission for an appeal against that order.