CAIRO -- Supporters and opponents of Egyptian President Mohammed Morsi clashed in fierce battles outside the presidential palace Wednesday, pelting each other with rocks, throwing Molotov cocktails and tear gas canisters and chasing one another around the compound in a melee that left five dead and more than 697 people injured.

The mayhem marked a new escalation in a divisive political crisis, over the prospect of a new constitution, that shows no signs of subsiding. The man Morsi appointed two days ago to oversee the Dec. 15 referendum on the document, Zaghloul El-Balshi, reportedly resigned, telling a TV interviewer, “I will not participate in a referendum that spilled Egyptian blood.”

Both sides of the dispute remain passionate that they represent the spirit of the revolt that led to the toppling of former Egyptian President Hosni Mubarak nearly two years ago. Morsi’s supporters say that as the nation’s first democratically elected president, he is trying to rid the government of Mubarak holdovers. Opponents argue that Morsi has grabbed power illicitly and that the Muslim Brotherhood, the group through which Morsi gained prominence, is behaving thuggishly, intimidating judges and private citizens alike.

Those disagreements had been aired relatively peacefully until Wednesday, when partisans set upon one another in the worst violence Egypt has seen since the 2011 anti-Mubarak protests.

“It’s a clash between two groups who believe they are good guys. It’s tragic. If I were the old regime, I would be laughing and saying this is what happens in revolutions,” said Noah Feldman, a law professor at Harvard University who has closely tracked Egyptian developments.

Who started the clashes was unclear as each side blamed the other. Even the role of the police was in dispute.

One anti-Morsi activist, Salma Said, said police officers allowed members of the Brotherhood to cross their lines to attack anti-Morsi demonstrators.

Police made no obvious moves to separate the two sides, however, and the tear gas that enveloped the scene apparently originated with the demonstrators themselves.

There was no sign that Morsi was willing to meet opposition demands that he cancel the referendum and withdraw a Nov. 22 decree that declared his decisions above review by the country’s courts.

Mahmoud Mekki, Morsi’s vice president, called for dialogue but said Morsi would not meet those demands. He said the opposition must forsake its efforts to pressure Morsi with massive street demonstrations, calling such efforts “unacceptable.”

“We have to get rid of this phenomenon of showing force in the street. We should calm down and communicate through constructive dialogue,” Mekki said.

Another Morsi adviser put the conflict in warlike terms.

“This is the final battle of revolutionaries and counterrevolutionaries,” Essam al Aryan, who belongs to the Brotherhood, told al Jazeera English.

Morsi’s opponents, meanwhile, took steps to bring order to what even they acknowledged had been a movement riven by political rivalries and disorganization. An umbrella group that had struggled to name a leader announced that it had agreed that Mohamed ElBaradei, the former director-general of the International Atomic Energy Agency, would lead the group.

ElBaradei then spoke in dire terms, using the word “regime” to describe Morsi’s government.