"Don't abandon the ANC to those involved in state capture and corruption," ANC stalwarts said in a statement on Friday reacting to former MP Makhosi Khoza's decision to quit the party.
The group of 101 stalwarts said while Khoza's decision to leave "appears rational", she should have stayed to end the "nightmare engulfing the country".
"If honest members of the ANC either leave or are silent, the legacy that will be remembered will not be the role played in the liberation struggle, our constitutional democracy and the development of a social welfare system, but the stench of corruption," the stalwarts said.
Khoza resigned from the African National Congress on Thursday during a media briefing, labelling the party alien and corrupt. She said the party's leadership had lost legitimacy and credibility.
At the time of her resignation, she was facing a disciplinary inquiry in her home province of KwaZulu-Natal after calling for President Jacob Zuma to step down and defending her decision to vote with her conscience in the motion of no confidence against Zuma in August.
The 101 stalwarts, who have been pushing for ANC renewal, said Khoza joins many others who have resigned or let their membership lapse because they could no longer be associated with a leadership that had placed self-enrichment above ANC policies.
"We cannot allow an ever-increasing vacuum to be created, to be only filled by those who want to use and abuse their membership, to steal the future of our country from our children and youth. We must re-find our collective voices that will again mobilise a country sickened by what [it sees]," the stalwarts said.
The stalwarts are due to hold a national consultative conference in October.
They wanted the conference to be held before the ANC's policy conference in July, but their proposal was rejected by the party, which instead dedicated two days of the July conference to organisational renewal.