Harare - Robert Mugabe faced the threat of impeachment by his own party on Monday, after his shock insistence he still holds power in Zimbabwe despite a military takeover and a noon deadline to end his 37-year autocratic rule.In a televised address late Sunday, the 93-year-old veteran leader defied expectations he would quit, pitching the country into a second week of political crisis.The speech provoked anger and disbelief among many Zimbabweans, fuelling concerns that Mugabe could face a violent backlash.His once-loyal Zanu-PF party - who has already sacked him and told him to resign as head of state -- warned it would seek to impeach him if he failed to quit by midday. The party has yet to comment on its next steps after that deadline passed.The army was expected to hold a briefing in response to the crisis triggered by Mugabe's refusal to go.As the Zanu-PF deadline passed, a noisy group of demonstrators gathered at the University of Zimbabwe in Harare to call for Mugabe to stand down.Mugabe's speech capped an extraordinary weekend that saw Zimbabweans celebrate and vent their anger in ways that, just a week earlier, would have been brutally repressed.But their joy quickly turned to despair as Mugabe brushed aside the turmoil -- blithely declaring he would chair a top-level meeting of the party that had just disavowed him.'He's lost his marbles'Chris Mutsvangwa, head of the influential war veterans' association, called for less restrained protests than those staged at the weekend in an effort to dislodge Mugabe."Save the country further turmoil. If not, we are bringing the people of Zimbabwe back to the streets," he said Monday, as he also threatened legal action against the president."This time there will be a sit-in. We are not going to be leaving Harare until this guy is gone."He's lost his marbles."Though Mugabe has struggled with public speaking in recent years, the wily statesman appeared alert and attentive as he delivered his speech that made no mention of stepping down."We will continue with the momentum to make sure Mugabe is history. It might take days and weeks, but Mugabe is on how way out," said Charles Muramba, a 46-year-old bus driver."Arrogant Mugabe disregards ZANU-PF," screamed the front page of the Daily News on Monday.The crisis erupted on November 13 over a factional squabble to succeed the ailing president.Mugabe's wife Grace, 52, secured prime position to succeed him, sidelining the vice president, Emmerson Mnangagwa, who was fired.But Mnangagwa, 75, has close ties to the army and the powerful war veterans.After he fled abroad, the army took over the country and placed Mugabe under house arrest.The army has insisted its action does not amount to a coup but was intended as a police action to arrest allegedly corrupt supporters of the highly ambitious first lady.When Mugabe refused to step down following behind-the-scenes talks, the generals unleashed people power.In scenes reminiscent of Zimbabwe's independence in 1980, crowds packed the cities, waving flags and chanting for Mugabe to resign.On Sunday Zanu-PF dismissed him as its leader and demanded he resign as head of state, naming Mnangagwa as the new party chief.But impeaching Mugabe, who is the only leader most Zimbabweans have ever known, would require a two-thirds supermajority in both houses of Zimbabwe's parliament which is due to resume on Tuesday.Unruffled Mugabe seemed unfazed in his speech and made no reference to the hostile chorus calling for him to go, describing last week's dramatic military intervention as "no threat" to his rule.Derek Matyszak, an analyst at the Pretoria-based Institute for Security Studies, said Mugabe's address raised the stakes even further."It's absolutely astounding. Mugabe behaves as if nothing Zanu-PF said (Sunday) was of any relevance," he told AFP.Some sources suggest Mugabe has been battling to delay his exit in order to secure a deal that would guarantee future protection for him and his family.Mugabe was a key figure in the war that wrested power from the white colonial government that ran the former Rhodesia.He took office as prime minister in 1980, surfing a wave of goodwill, and later became president.But his reputation was swiftly tarnished by his authoritarian instincts, rights abuse and economic ineptitude. Eventually his country was shunned by the West.Output has halved since 2000 when many white-owned farms were seized, leaving the key agricultural sector in ruins.