Egypt's opposition Rebel (Tamarod) campaign has rejected proposals for a referendum on whether President Mohamed Morsi should complete his term.
Rebel said via Twitter on Tuesday that the president "has no option but to leave along with Prime Minister [Hisham Qandil] and the Shura Council [upper house of parliament]."
On Sunday, millions of people attended protests called for by the campaign, and supported by major opposition groups, demanding that Morsi steps down.
Sixteen people died on Sunday in clashes between the president's supporters and opponents.
Rebel also said any attack on opposition protesters would be the direct responsibility of the president and called upon the military and police to protect "peaceful protesters."
On Monday, the Egyptian Armed Forces issued a televised statement giving political forces 48 hours to "fulfil the people's demands," otherwise it would present a political "roadmap" for the country that would include all political currents.
Amid speculation that the army would stage a military coup, the armed forces released a later statement saying that army doctrine does not support military coups.
Many opposition political forces hailed the army's statement and repeated their demand for early presidential elections.
Islamist forces headed by the Muslim Brotherhood are holding an open-ended demonstration at Rabaa El-Adawiya Mosque in Cairo's Nasr City in support of Morsi's "legitimacy". Pro-Morsi rallies were reported late Monday in several governorates.
The Rebel campaign on Saturday announced it had collected 22 million signatures calling for Morsi's removal, more than its target of 15 million.