A political source who spoke to senior allies holed up with Mugabe and his family in his lavish "Blue House" Harare compound said Mugabe had no plans to resign voluntarily ahead of elections scheduled next year.
"It's a sort of stand-off, a stalemate," the source said. "They are insisting the president must finish his term."
The army's takeover signalled the collapse in less than 36 hours of the security, intelligence and patronage networks that sustained him through 37 years in power and built him into the "Grand Old Man" of African politics.
The army appears to want Mugabe, who has led Zimbabwe since independence in 1980, to go quietly and allow a smooth and bloodless transition to former vice-president Emmerson Mnangagwa.
Still seen by many Africans as a liberation hero, Mugabe is reviled in the West as a despot whose disastrous handling of the economy and willingness to resort to violence to maintain power pauperised one of Africa's most promising states.
A fighter, both literally and figuratively during a political career that included several assassination attempts, Mugabe now appears to have reached the end of the road.
Zimbabwean intelligence reports seen by Reuters suggest his exit has been in the planning for more than a year.
Mnangagwa, a former security chief and life-long Mugabe confidant known as "The Crocodile" who was axed as vice-president earlier this month, is the key player.
According to the files and political sources in Zimbabwe and South Africa, once Mugabe's resignation is secured Mnangagwa would take over as president of an interim unity government that will seek to stabilise the imploding economy.
"Solid hands"
Former finance minister Tendai Biti added to that speculation, telling Reuters he would be happy to work in a post-coup administration as long as Tsvangirai was also on board.
"If Morgan says he's in, I'm in," said Biti, who earned international respect during his time as finance minister in a 2009-2013 unity government. "The country needs a solid pair of hands so one might not have a choice."
South Africa said Mugabe had told President Jacob Zuma by telephone on Wednesday that he was confined to his home but was otherwise fine and the military said it was keeping him and his family, including wife Grace, safe.
Dubbed "DisGrace" or "Gucci Grace" on account of her reputed love of shopping, she enjoyed a meteoric rise through the ranks of Mugabe's ZANU-PF party in the last two years, culminating in Mnangagwa's removal a week ago.
Zimbabweans, including the Mnangagwa camp and the military, interpreted this as a move to clear the way for her to succeed her husband.
In contrast to the high political drama unfolding behind closed doors, the streets of the capital remained calm, with people going about their daily business, albeit under the watch of soldiers on armoured vehicles at strategic locations.