South Africa's ruling African National Congress (ANC) rallied behind President Jacob Zuma on Friday, saying its lawmakers would have to be "bewitched" to vote for a no-confidence motion on Tuesday that could remove the scandal-prone leader.
Zuma (75) has suffered a string of judicial and political setbacks since he took office in 2009, but has held onto power with the backing of his party, which dominates parliament.
In July, South Africa's top court ruled that secret ballots can be held for motions of no confidence if the speaker of parliament so decides.
Zuma's critics want the no confidence vote brought by the main opposition Democratic Alliance (DA) party to be anonymous, hoping it will embolden ANC lawmakers to support his removal by shielding them from pressure from other party members.
The DA and civil society groups said they would hold a march billed as "the last push" on Tuesday outside the parliament in Cape Town.
"We cannot be defeated by one man. It is now or never!" a statement by the DA, other parties and the civil society groups said. "While the removal of Zuma will not solve every problem in our nation, it would be the beginning of a national rebuilding project that is urgently required."
ANC parliamentary chief whip Jackson Mthembu said the party would vote as a bloc against the motion.
"We cannot, with our eyes open, assist our nemesis to remove the government from power," Mthembu told a news conference in Cape Town. "It's only a bewitched party that would do so. Nobody in his right mind will do so."
A motion of no confidence requires a simple majority to pass, in this case 201 votes in the 400-member parliament.
If the motion succeeds, Zuma - who has survived eight previous motions of no confidence - and his entire cabinet would have to step down.
Mthembu said voting for the motion would be "tantamount to throwing a nuclear bomb on ourselves" that would unleash political and economic hardship in South Africa.
Africa's most industrialised economy has sunk into recession and had its credit rating downgraded to junk by two of the three main credit rating agencies. Unemployment is at a 14-year high of 27.7 percent and business confidence is sagging.
Mthembu accused Julius Malema, a former protege of Zuma who now leads the far-left Economic Freedom Fighters party, of wishful thinking for saying more than 60 ANC members in parliament will back the no-confidence vote.
"I've seen and heard other party leaders saying that there are about 60 MPs of the ANC who will be putting their vote in the positive bloc. We are saying there is no such," Mthembu said.