Party chiefs will meet today to draft a resolution laying the ground for the president, currently under house arrest, to be removed from office.
A source said: “There is no going back.
“If he becomes stubborn, we will arrange for him to be fired on Sunday. When that is done, it’s impeachment on Tuesday.”
The fate of Mr Mugabe, who has ruled the country for 37 years, has hung in the balance after military chiefs seized control of the country this week.
On national television, the military said it was holding talks with the 93-year-old on the way forward and that it would advise the nation on their outcome as soon as possible.
There had been confusion over what would happen when a smiling Mr Mugabe was pictured shaking hands with Zimbabwe’s military chief, the man behind the coup.
The leader unexpectedly drove on Thursday from his lavish “Blue Roof” compound, where he had been confined, to State House, where official media pictured him meeting military boss Constantino Chiwenga and South African mediators.
It is thought the army want Mr Mugabe to go quietly and allow a smooth and bloodless transition to Emmerson Mnangagwa, the vice president Mugabe sacked last week, triggering the crisis.
But the main goal of the generals is to prevent him handing power to his wife, Grace, 41 years his junior.
She has built a following among the ruling party’s youth wing and appeared on the cusp of power after Mnangagwa was pushed out.
Mr Mugabe, who has appeared increasingly frail in public, has insisted he remains Zimbabwe’s only legitimate ruler and is refusing to quit.
But pressure was mounting on the former guerrilla to accept offers of a graceful exit.
More to follow.