CAIRO -- With millions of Egyptians in the streets for a third straight day demanding his resignation, a defiant President Mohammed Morsi took to Egypt’s airwaves early Wednesday morning and vowed to fight to remain in office, even if “the price is my blood.”

In a 40-minute call to arms to his supporters, Morsi angrily declared his right to serve out his term as the first democratically elected president in Egypt’s long history.

“I am the president of Egypt,” he shouted at one point. “There is no substitute for legitimacy, no alternative.”

The speech seemed to augur the likelihood of violence when a 48-hour deadline issued by the military calling for Morsi and his opponents to find a solution to their impasse expires at 4:30 p.m. (10:30 a.m. EDT).

“The price can be my life,” he said.

The speech was likely to be read as a call to arms by thousands of Muslim Brotherhood members who’ve been forming their own security force, armed with sticks, helmets and Molotov cocktails, even as police and the country’s military seemed to be withdrawing their support from Morsi.

Keeping their distance from anti-Morsi protests that have brought millions into the streets, Brotherhood forces have been preparing for days, chanting, lining up in formation, and hoisting sticks, chair legs and two-by-fours in mock combat drills.

Mohamed ElBaradei, the former head of the International Atomic Energy Agency who leads the largest opposition group, the National Salvation Front, was reported to be negotiating with the Morsi government. But whatever, if anything, emerges from that effort is unlikely to satisfy everyone, portending, under the best of circumstances, even more instability.

That made the potential for violence high. Even on a relatively peaceful day, with people just waiting for Wednesday, at least four people were killed and 149 injured.

In one incident witnessed by McClatchy reporters in the Kit Kat neighborhood of Cairo’s Giza district, Morsi supporters had to be rescued after a group of residents swarmed them. Shots were fired, a police van arrived and the injured Brotherhood members were swooped away.

Elsewhere in Cairo, the Muslim Brotherhood seemed determined to secure Morsi’s legitimate place as Egypt’s leader with its illegitimate security force.

“Strength, determination, faith, Morsi’s men are everywhere!” they screamed while stomping their feet and doing air punches in the air. Overweight men in beards then dropped down and began doing pushups.

The tension was high as they waved their sticks in the air and stomped their feet in front of the presidential palace. Their numbers had clearly grown from Friday, when they’d formed up in squad-size units of 15 to 20; on Tuesday, they were organized in platoons, 50 or 60 men to a unit.

One group donned blue construction helmets and orange life vests to serve as protection from rubber bullets. Another wore red and silver motorcycle helmets; its members carried green pipes. They vowed to battle to the death.

Some had written “martyr” on their orange vests. Others carried signs that read: “Martyr Project.”

“I am prepared to be martyred,” one man told another.

If they succeed in defending Morsi’s hold on the presidency, it’s unclear what Morsi would control. On Monday, the military leadership, the Supreme Council of the Armed Forces, gave Morsi and his opponents 48 hours to outline a “roadmap” for reconciliation. If they don’t come to consensus, the military said it would “intervene.”