Zuma was expected to respond on Wednesday to an order from the ANC to resign as head of state, party officials said.
The ANC's national executive committee reached the decision after meeting for 13 hours at a hotel outside Pretoria.
But the reason his demise now seems inevitable is because his party, the African National Congress, appears to have judged that he's too much of an electoral liability.
The sribe of the ANC, told a news conference that Zuma was preparing to the decision to "recall" him.
"I think what we expect now is that the deadline which has been set for the president by the NEC is for tomorrow [Wednesday]".
Zuma's hold over the ANC was shaken in December when his chosen successor - his former wife Nkosazana Dlamini-Zuma - narrowly lost to Ramaphosa in a vote to be the new party leader.
But Magashule said the ANC did not recall the president for any wrongdoing.
Zuma's presidency has been marred by slow economic growth, continuing racial inequality and record unemployment that have fuelled public frustration.
What has Mr Zuma done wrong?
"Once you resist we are going to let you be thrown out through the vote of no confidence because you disrespect the organisation and you disobey it, therefore we are going to let you be devoured by the vultures", Mantashe said in a message to Zuma, according to the Independent.
"The collective of the ANC believe that (party) president Cyril Ramaphosa must take over the (national) presidency".
Another analyst, Sipho Seepe, told Xinhua that the ANC needs to sort its internal pressure and renew itself.
He said Ramaphosa would deliver the state of the nation address to Parliament in coming weeks.
Magashule said Zuma asked for three to six months to complete the job, but said the party felt that was too long, given his sinking approval ratings as critical elections approach next year.
"We cant wait. It's not fair to South Africans".
Zuma still commands significant support and respect in the party, as a prominent member of the struggle against apartheid.
It wants to project a fresh image for next year's general election. Mr Zuma's slow defenstration is a distraction from the work of government. Opposition parties are calling for another vote of no confidence against Zuma next week.
Ramaphosa past year accused Zuma of rape.
Zuma is expected to make a decision on whether he will resign on Wednesday.
"Unless Zuma tenders his resignation, this recall is not worth the paper it is printed on", he wrote on his verified Twitter account.
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