The Congress of the People has 428,000 paid-up members and that could swell to half a million by its inaugural conference at the weekend, COPE general secretary Charlotte Lobe said on Tuesday.
The Eastern Cape is clearly the breakaway party's stronghold with 160,000 members, followed by the Free State with 74,000 and the Western Cape with 60,000, Lobe told a media briefing.
She said the party had counted only those followers who had completed registration forms and paid the annual membership fee of R30.
COPE on Tuesday unveiled its preliminary policy framework a week ahead of the party's formal launch in Bloemfontein.
The draft manifesto focuses on encouraging economic growth and employment, giving South Africans better social security and stepping up the fight against crime and HIV/AIDS.