The Zimbabwe African National Union-Patriotic Front, the ruling party in the African nation, on Monday said it had no confidence in the leadership of Robert Mugabe, who on Sunday refused to step down from the presidency despite the growing clamour for his resignation.

The party had asked Mugabe to quit by midday on Monday.

In its impeachment motion – unveiled after a meeting of lawmakers at the party headquarters in on Monday afternoon – the Zanu-PF said it was “gravely concerned that the president has become the country’s source of instability” and was alarmed that he had handed over his constitutional mandate to his wife Grace.

Three unidentified senior party officials were quoted by Bloomberg as saying that Mugabe had deviated from an agreed-upon text, and impeachment proceedings against him may begin as early as Tuesday.

Although the ruling party has the required two-thirds majority to remove the president, lawmakers from the main Opposition party, the Movement for Democratic Change, will meet on Tuesday to decide whether to support Zanu-PF’s impeachment motion, Reuters reported.