The National Prosecuting Authority (NPA) must immediately institute charges against President Jacob Zuma, the Economic Freedom Fighters (EFF) said on Friday.
"The best way to restore the integrity of the NPA is to proceed and charge Zuma, who must, in turn, step down from the highest office in the land," said EFF spokesperson Mbuyiseni Ndlozi.
Ndlozi was responding to the Supreme Court of Appeal's (SCA's) ruling on Friday, which dismissed the appeal brought by Zuma and the NPA, in relation to the reinstatement of corruption charges against the President.
The appeal was dismissed with costs.
Ndlozi said, while the EFF welcomed the ruling, action should be taken against Zuma immediately.
"Zuma's continued occupation of office undermines the ability to uphold the rule of law. Not only has he broken the Constitution, he has done everything in his power to avoid facing corruption charges.
"He is the greatest living threat to democracy and respect for the rule of law. He must step down and face the full might of the law," said Ndlozi.
Zuma and the NPA had approached the SCA, seeking leave to appeal the 2016 decision by the North Gauteng High Court in Pretoria relating to the "spy tapes" saga.
The 18 charges against Zuma were withdrawn in 2009, just before he was sworn in for his first term as president, but the Democratic Alliance wanted the charges to be reinstated.
In 2016, a full bench of judges overturned the NPA's decision to drop the corruption charges against Zuma that related to fraud, racketeering and money laundering.
Both the NPA and Zuma turned to the SCA after the High Court denied them direct access for an appeal.
But last month, Zuma and the NPA made an about-turn and conceded that Mokotedi Mpshe's decision not to prosecute Zuma was irrational.