Zimbabwean President Robert Mugabe is said to have pleaded for "a few more days" in power as an influential group of military veterans warned his time was up.
The group's leader Chris Mutsvangwa, an ally of the recently fired vice-president Emmerson Mnangagwa, said they would "settle the scores tomorrow" if Mr Mugabe did not step down.
Zimbabwe remained in political limbo on Friday as the President looked to resist attempts to oust him following this week's military takeover.
Mr Mutsvangwa said Mr Mugabe had asked for "a few more days, a few more months" amid negotiations with army chiefs over the end of his reign.
He told reporters in Zimbabwe's capital Harare that "between now and tomorrow" they will warn the President that the game up.
"He has to make a decision today to leave," he said "If he doesn't leave, we will settle the scores tomorrow."
Mr Mutsvangwa is chairman of the Zimbabwe National Liberation War Veterans Association, which has close ties with and influence over Mr Mugabe's ruling Zanu-PF party.
The 93-year-old has insisted he remains in charge but looks almost certain to be forced from office, with his party stating there "is no going back".
Senior Zanu-PF figures were set to meet on Friday to draft a resolution to dismiss Mr Mugabe and lay the ground for his impeachment if he refuses to stand down.
"If he becomes stubborn, we will arrange for him to be fired on Sunday," a senior party source said. "When that is done, it's impeachment on Tuesday."
Mr Mutsvangwa described President's appearance at a university graduation ceremony on Friday as a "pretence". It was the first time the President had been seen in public since being placed under house arrest.
The war veterans leader said they were "on the same page" with South Africa's government, which has sent Cabinet ministers to negotiate with Mr Mugabe.
The President of Botswana, Zimbabwe's neighbour, was among those calling for Mr Mugabe to go on Friday. Ian Khama said Mr Mugade had no diplamatic support in the region, adding military intervention presented "an opportunity to put Zimbabwe on a path to peace and prosperity".
He added: "I don't think anyone should be President for that amount of time. We are Presidents, we are not monarchs. It's just common sense."
Mr Mugabe was taken into military custody on Tuesday night during what the army described as a "bloodless correction".
He was placed under house arrest at palatial presidential residence, Blue Roof, along with his wife Grace and some of his senior supporters.
There was no sign of his Ms Mugabe, whose whereabouts were unclear, as her husband appeared at the graduation ceremony on Friday.
Her political ambitions in part led to this week's military takeover. The 52-year-old had been calling for Mr Mnangagwa's removal for weeks as the two fought an increasingly bitter winner-takes-all contest to succeed Mr Mugabe, Zimbabwe's only leader since independence from Britain in 1980.
Mr Mugabe on Thursday rejected a proposal under which he would step down allowing Mr Mnangagwa, nicknamed "The Crocodile", to take over temporarily until elections due to be held next year.
The President insisted he remains the legitimate head of state and has asked for guarantees if he were to leave sometime in the future. He is said to have demanded that there would be immunity from prosecution for his wife and other members of his family.
It remains unclear whether General Constantino Chiwenga, the head of the military, would agree to the President’s demand to spare his wife from prosecution. There are growing calls for charges to be made against Ms Mugabe and her cohort for alleged embezzlement and abuse - charges Ms Mugabe has denied.
Zimbabwe's military said it was continuing talks with President Mugabe on Friday as it continued to pursue "criminals" who were close to the leader and his wife.
In a statement reported by state media, the army said "significant progress has been made in their operation to weed out criminals around President Mugabe," adding some arrests had been made but others were still at large.
The statement added Zimbabwe's military was is "currently engaging with the Commander-in-Chief President Robert Mugabe on the way forward and will advise the nation of the outcome as soon as possible."
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