South Africa's governing ANC has chosen two bitter rivals, President Thabo Mbeki and Jacob Zuma, as the sole candidates for the party leadership.
The ANC Women's League had been expected to back Mbeki
The vote at the party's fractious conference is now due on Tuesday after two days of gruelling debate in which their rivalry emerged for all to see.
Proceedings have been rowdy and at times confrontational despite appeals from former President Nelson Mandela.
Mr Zuma is the favourite to win but Mr Mbeki's camp is increasingly vocal.
Some had hoped a compromise candidate would be nominated to help end the divisive contest between Mr Mbeki and his former ally, the BBC's Will Ross reports from the conference in Polokwane, Limpopo.
But there were no new nominations and now on Tuesday almost 4,000 members of the African National Congress will have to choose between the two men.
The election has a significant influence on who will become the next president of South Africa, our correspondent notes.
Thabo Mbeki, 65
Succeeded Nelson Mandela as president in 1999
Presided over economic growth
Accused of not doing enough to reduce poverty
Won bid to host 2010 football World Cup
Seen as aloof
From Xhosa ethnic group
Jacob Zuma, 65
Played key role in fight against apartheid
Plagued by corruption allegations
Backed by trade unions, Communist Party
Seen as charismatic
From Zulu ethnic group
After two terms in office, President Mbeki is obliged to step down but should he win the party leadership contest he could work to prevent Mr Zuma from reaching the presidency.
It has been the most divisive contest in the long history of the ANC, our correspondent adds.
For some this is a sign of a healthy democracy in action while others, he says, fear the split in the ANC could spell trouble for South Africa.
Delegates were warned to behave or face disciplinary action on Monday after Mbeki supporters tried to out-sing each other amid chaotic scenes.
Zuma supporters sang the anti-apartheid song Bring Me My Machine-gun, during pro-Mbeki speeches while Mbeki supporters retorted by singing Mbeki, My President.
Mr Mbeki had been booed and heckled during his opening speech on Sunday.
Jeff Radebe, a member of the ANC's national executive committee, said "appropriate action" would be taken if booing persisted.
"Intimidation is beginning to affect our people," said one Mbeki supporter, Deputy Defence Minister Mluleki George.
It will be the ANC's first leadership contest in 58 years.
In an address lasting nearly three hours on Sunday, Mr Mbeki did not mention Mr Zuma by name but stressed the need for "ethical leadership".
Mr Zuma has been warding off allegations of corruption and last year was acquitted of rape charges - he says they were politically motivated.
Mr Mbeki said claims by the Zuma camp that he had centralised power were false.
Mr Mandela has said he is saddened by "the nature of the differences currently in the organisation".
On Friday, the former Archbishop of Cape Town, Desmond Tutu, said neither Mr Zuma or Mr Mbeki were suitable candidates.
Once close allies, Mr Zuma and Mr Mbeki publicly fell out in 2005 when Mr Zuma was sacked as deputy president over corruption allegations.
The case against Mr Zuma was thrown out by a judge last year but he could still face charges in connection with a multi-million dollar arms deal.
Mr Zuma's supporters believe he would do more to reduce poverty in South Africa.