South Africa's ruling African National Congress (ANC) has formally asked President Jacob Zuma to resign after he refused to do so earlier, reports say.
The reported decision to "recall" him followed marathon talks by senior party officials that continued into the early hours of Tuesday.
If Zuma, 75, still does not budge, he will face a vote of confidence in parliament that he is expected to lose.
In power since 2009, he has been dogged by corruption allegations.
The ANC has not officially confirmed its plans but party sources have described them to South African media outlets and Reuters news agency.
Zuma has resisted increasing pressure to quit since December, when Cyril Ramaphosa replaced him as leader of the ANC.
ANC secretary-general Ace Magashule visited the embattled president at his official residence in the capital, Pretoria, and officially informed him of the party's decision to "recall" him at a meeting of its top leadership body, the national executive committee (NEC), reports say.
It is unclear how Zuma responded, and his office has not yet commented.
Earlier, Ramaphosa left the meeting of the ANC's NEC to travel to Zuma's residence, where he is said to have told the president he would be "recalled" if he did not step down. He later returned to the ANC conclave.
Zuma's presidency has been overshadowed by allegations of corruption which he has always vehemently denied.
In 2016, South Africa's highest court ruled that Zuma had violated the constitution when he failed to repay government money spent on his private home.
Last year the Supreme Court of Appeal ruled that he must face 18 counts of corruption, fraud, racketeering and money laundering relating to a 1999 arms deal.
More recently, Zuma's links to the wealthy India-born Gupta family, who are alleged to have influenced the government, have caused his popularity to plummet.
Both Zuma and the Guptas deny the allegations.
Correspondents say it will be very difficult for him to resist a formal request to resign but he would not be legally obliged to do so and could technically carry on as president despite losing the faith of his party.
However, he would then be expected to face a confidence vote in parliament. This has been scheduled for 22 February, but it could be held earlier.
Zuma has survived other such votes but he is not expected to pull it off again. A confidence vote would be considered a humiliating process for him and the party.
South African media are calling President Zuma's seemingly inevitable exit "Zexit".
His predecessor, Thabo Mbeki, resigned in 2008, also after a power struggle with his deputy.
The deputy in question was Jacob Zuma, who took over the presidency the following year.
Source: News Agencies, Edited by website team