HARARE (Reuters) - Zimbabwe’s ruling ZANU-PF party called on Friday for President Robert Mugabe to resign, the main state newspaper The Herald reported, the latest sign that the aging leader’s authority has collapsed after an army takeover.

The newspaper said that ZANU-PF branches in all 10 provinces had met on Friday and had also called for Mugabe’s wife Grace, whose ambitions to succeed her husband triggered the unfolding political crisis, to resign from the party.

Mugabe appeared in public on Friday for the first time since the army took charge, as the ruling party made plans to force him to step down after almost four decades in power.

The president, who is 93, opened a graduation ceremony at Zimbabwe Open University in Harare. He wore blue and yellow academic robes and a mortar board hat and appeared to fall asleep in his chair as his eyes closed and his head lolled.

Mugabe led the country’s liberation struggle and has dominated its politics since independence in 1980.

A senior member of the ZANU-PF ruling party said it wanted him gone.

“If he becomes stubborn, we will arrange for him to be fired on Sunday,” the source said. “When that is done, it’s impeachment on Tuesday.”

The Herald reported that ZANU-PF would convene a special Central Committee meeting on Sunday to “realign the revolutionary party with current political developments.”

The military, which seized power on Wednesday, has so far treated Mugabe carefully. It said in a statement on national television it was “engaging” with Mugabe, referred to him as Commander in Chief and said it would announce an outcome as soon as possible.

ZANU-PF has also called for a mass meeting in the capital on Saturday to show its support for the War Veterans group in their bid to remove Mugabe.

The veterans, Mugabe’s former comrades from the liberation war, who enjoyed a privileged position under his rule for decades, had chafed in recent years as his wife Grace positioned herself to succeed him. They finally turned on him decisively after he sacked Vice President Emmerson Mnangagwa last week.

The Herald newspaper on Friday said that ZANU-PF wanted Mnangagwa reinstated as vice president because he was dismissed “without endorsement of the central committee”.

Many Zimbabweans suspect the military’s plan is to hand power to Mnangagwa, a long-serving Mugabe confidant and liberation war veteran nicknamed “the Crocodile”. If so, the generals may be waiting until Mnangagwa can be reinstated as vice president before arranging for Mugabe to resign.

Mugabe is revered as an elder statesman and independence leader but he is also viewed by many in Africa as a president who crippled his country by remaining in power too long. He calls himself the grand old man of African politics.

“NO GOING BACK”

Zimbabwe’s official newspaper, the Herald, ran photographs late on Thursday showing Mugabe grinning and shaking hands with military chief General Constantino Chiwenga, who led the army takeover.

The images stunned Zimbabweans who said it meant Mugabe was managing to hold out against Chiwenga’s coup. Some political sources said he was trying to delay his departure until elections scheduled for next year.

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The ZANU-PF source said he would not be able to stay that long. Anxious to avoid a protracted stalemate, party leaders were drawing up plans to dismiss Mugabe at the weekend if he refused to quit, the source said.

“There is no going back,” the source told Reuters. “It’s like a match delayed by heavy rain, with the home side leading 90-0 in the 89th minute.”

The army is camped on his doorstep. Grace Mugabe is under house arrest and her key political allies are in military custody. The police, once a bastion of support for Mugabe, have showed no signs of resistance to the army.

Furthermore, he has little popular backing in the capital, a stronghold of support for opposition parties that have tapped into the anger and frustration at his handling of the economy, which collapsed after the seizure of white-owned farms in 2000.

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After stabilising briefly when Mugabe was forced to work with the opposition in a 2009-2013 unity government, the economy has collapsed again.

Unemployment is now running at nearly 90 percent and chronic shortages of hard currency have triggered hyperinflation, with the prices of imports rising as much as 50 percent a month.

Mugabe has won a series of elections but his critics in Africa and the West say his handling of the economy has been disastrous and he has used violence to maintain power. Botswana’s President Ian Khama told him to resign.

“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,” Khama said.

Still, African states are keen that whatever outcome is achieved in Zimbabwe, it happens within the framework of the constitution, which may give Mugabe some leverage over the terms of his departure.

“We note with great concern the unfolding political development in Zimbabwe and we hope that they will not lead to unconstitutional change of government,” South African President Jacob Zuma said at a Southern African Development Community meeting in Botswana’s capital Gaborone.

Dumiso Dabengwa, a Zimbabwean liberation war veteran and KGB-trained former intelligence chief, said Mugabe’s fate was sealed but old age was causing him to dig in his heels.

“At his age, everybody becomes very stubborn and he would be no exception,” he told reporters in Johannesburg.

“He certainly will not do it easily, but I think the people will show him that he’s no longer wanted.”

U.S. Secretary of State Rex Tillerson on Friday urged “a quick return to civilian rule” in Zimbabwe.

“Zimbabwe has an opportunity to set itself on a new path, one that must include democratic elections and respect for human rights,” Tillerson told African foreign ministers ahead of a meeting in Washington.

(For a graphic on 'Zimbabwe's struggling economy' click here)