CAIRO -- The fate of Egypt's first democratically elected president hung in the balance Tuesday, hours before a deadline to yield to the demands of millions of protesters or see the military suspend the constitution, disband parliament and install a new leadership.
Embattled Islamist President Mohammed Morsi vowed not to resign, however, and he demanded that the powerful armed forces withdraw their ultimatum, saying he rejected all "dictates" -- from home or abroad.
In a speech to the nation, he pledged to protect his "constitutional legitimacy" with his life and accused loyalists of his autocratic predecessor Hosni Mubarak of riding the current wave of protests to topple his regime.
"There is no substitute for legitimacy," said Morsi, who at times angrily raised his voice, thrust his fist in the air and pounded the podium. He warned that electoral and constitutional legitimacy "is the only guarantee against violence."
Morsi's defiant statement sets up a major confrontation between his Islamist supporters and Egyptians angry over what they see as his efforts to impose control by his Muslim Brotherhood as well as his failure to introduce reforms more than two years after the Arab Spring revolution. His opponents say that he has lost his legitimacy through mistakes and power grabs and that their turnout on the streets shows the nation has turned against him.
Millions of jubilant, chanting Morsi opponents filled Cairo's historic Tahrir Square, as well as avenues adjacent to two presidential palaces in the capital, and main squares in cities nationwide. After Morsi's speech, they erupted in indignation, banging metal fences to raise a din, some raising their shoes in the air in a show of contempt. "Leave, leave," they chanted.
Morsi "doesn't understand. He will take us toward bloodshed and civil war," said Islam Musbah, a 28-year-old protester sitting on the sidewalk outside the Ittihadiya palace, dejectedly resting his head on his hand.
The president's supporters also increased their presence in the streets of the capital and other cities, after the Muslim Brotherhood and hard-line Islamist leaders called them out to defend what they say is the legitimacy of his administration.
At least seven people were killed in three separate clashes between his supporters and opponents in Cairo, according to hospital and security officials who spoke on condition of anonymity because they were not authorized to talk to the media. At least 23 people have died in political violence since the unrest began on Sunday, the first anniversary of Morsi's inauguration.
Morsi's supporters have stepped up warnings that it will take bloodshed to dislodge him, saying they would rather die fighting a military takeover than accept his ouster just a year after Egypt's first free election.
"Seeking martyrdom to prevent the ongoing coup is what we can offer as a sign of gratitude to previous martyrs who died in the revolution," Brotherhood stalwart Mohammed el-Beltagy wrote Tuesday in his official Facebook page.
Monday, the military gave Morsi an ultimatum to meet the protesters' demands within 48 hours. If not, the generals' plan would suspend the Islamist-backed constitution, dissolve the Islamist-dominated legislature and set up an interim administration headed by the country's chief justice, the state news agency reported.
The leaking of the military's so-called political "road map" appeared aimed at adding pressure on Morsi by showing the public and the international community that the military has a plan that does not involve a coup.
On his official Twitter account, Morsi urged the armed forces "to withdraw their ultimatum" and said he rejects any domestic or foreign dictates."
Fearing that Washington's most important Arab ally would descend into chaos, U.S. officials said they are urging Morsi to take immediate steps to address opposition grievances, telling the protesters to remain peaceful and reminding the army that a coup could have consequences for the massive American military aid package it receives. The officials spoke on condition of anonymity because they were not authorized to speak publicly.
Morsi adviser Ayman Ali denied that the U.S. asked Egypt to call early presidential elections and said consultations were continuing to reach national conciliation and resolve the crisis. He did not elaborate.
Morsi met with the army's chief, Defense Minister Gen. Abdel-Fattah el-Sissi, and Prime Minister Hesham Kandil in the second such meeting in as many days, Ali said, without giving details.
The army has insisted it has no intention to take power. But the reported road map showed it was ready to replace Morsi and make a sweeping change in the ramshackle political structure that has evolved since Mubarak's fall in February 2011.