Thousands of opposition protesters converged on Egypt’s presidential palace Friday night, breaking through barbed-wire barricades and chanting slogans against President Mohamed Morsi, in defiance of his call Thursday for a national dialogue to bridge the country’s expanding political divide.

Opposition leaders rejected Morsi’s invitation to meet for discussions on Saturday after more than two weeks of political crisis that has pitted the president and his Islamist backers against a broad coalition of liberals and secularists. Morsi’s critics said his speech to the nation Thursday and moves by his allies in the Muslim Brotherhood on Friday did more to fan the flames than quell them.

The competing rhetoric and scenes of defiance underscored how the population has been polarized as it struggles to define the balance of power in the country nearly two years after the forces now opposing each other joined hands in the mass uprising that ousted President Hosni Mubarak.

Amid calls for a delay to the scheduled Dec. 15 vote on a contentious draft constitution, Egypt’s High Election Commission said Friday that it would postpone overseas voting on the charter. The move raised hopes among some that Morsi might be moving toward making concessions.

But a spokesman for the Muslim Brotherhood, which backs Morsi, said Friday night that a delay to next week’s vote would be possible only if the opposition heeded the president’s invitation to dialogue.

On Saturday, Egypt’s military joined the call for dialogue, warning in a statement read on state TV of “disastrous consequences” if the political crisis gripping the country is not resolved. The military said that serious dialogue is the “best and only” way to overcome the nation’s deepening dispute.

A decree by Morsi last month that gave him the power to legislate without oversight yielded an unlikely alliance of disorganized opposition groups, including liberals, human rights activists, Christians and old-regime loyalists.

They differ on many things, including the concessions they hope to extract from Morsi and whether to vote against the constitution or boycott the referendum altogether if it goes to a vote as planned. But they agree that Egypt’s first democratically elected president has drastically overstepped his authority — and that protest is the only way to turn him around.

As the standoff enters its third week, politicians and activists on each side said that the flow of angry words and violent protest from the other side is cementing a dangerous divide that is likely to outlive the current crisis.

Some of the protesters who massed outside the palace Friday said that they had voted for Morsi — giving him “a chance to rule” — but that the president’s recent actions had left them feeling that he was no longer fit to lead Egypt and that the once-banned Muslim Brotherhood from which he hails could never again be trusted.

“He said he was the president of Egypt. But the truth is he’s the president for the Muslim Brotherhood,” said Amr al-Tahry, 20, a student at Egypt’s naval academy who said he voted for Morsi in the summer. “I was willing to try trusting the Muslim Brotherhood. Now — no, never.”

The military’s interests

In the wake of violence Wednesday night that left seven people dead and more than 400 injured, the military’s elite Republican Guard — charged with protecting the palace — deployed tanks and armored vehicles around the complex Thursday and ordered protesters to remain outside the perimeter.

But Friday night, thousands in the angry crowd breached that perimeter, and witnesses said the Guard withdrew behind the palace walls.

Analysts said the military has little interest in getting involved on either side of the conflict but has every interest in seeing the constitution approved. The charter, passed by an Islamist-dominated drafting assembly, would solidify the military’s power and privilege to a degree that surpasses even that of the Mubarak era.

An alliance of prominent opposition figures, calling itself the National Salvation Front, said in a statement Friday that the president’s invitation for a meeting Saturday failed to meet “the principles of real and serious negotiations” and displayed “the complete disregard” for the opposition’s demands.

Opposition leaders said they would not negotiate with Morsi until he cancels his Nov. 22 decree and calls off the Dec. 15 referendum on the draft constitution, which they said fails to enshrine the rights of women and minorities and puts too few limits on the president’s power.

Increasingly, however, the opposition has also called on Morsi to step down. Some protesters pointed to disarray within his administration this week, including the resignation of several presidential advisers, as indicators that the opposition would eventually have its way.

“Leave, leave!” protesters chanted as they marched to the palace Friday.

‘Their goal is not freedom’

Members of the Muslim Brotherhood also turned out Friday to show their support for Morsi. Thousands gathered outside Cairo’s al-Azhar mosque to hear a sermon by the Brotherhood’s leader and supreme guide, Mohammed Badie, and to witness the public funerals of group members who were killed in the recent clashes.

“Their goal is not freedom. It is power,” Mohamed Shaban, 21, a student who rallied in support of the president in one of Cairo’s satellite cities, said of the opposition.

“Most people in Tahrir Square are symbols of the old regime,” he said, echoing a popular refrain among Morsi’s supporters.

After Morsi’s speech Thursday night, anti-Morsi demonstrators looted and ransacked the Cairo headquarters of the Muslim Brotherhood, his political base, and a smaller outlying office. On Friday night, Brotherhood supporters called for rallies at points near the palace and promised to protect the compound if it was breached by protesters.

Meanwhile, the attorney general’s office said Friday that it had opened investigations into three top opposition figures for instigating the violence.

Both sides said that each drop of “spilled blood” has rendered the chance of a compromise increasingly unlikely.

“Those people [in the Brotherhood] have been thinking about coming to power for 85 years,” said Sherihan Sharabi, 27, an actress who has camped in Tahrir Square since Morsi issued his decree two weeks ago. “They’re not going to leave without bloodshed.”

Sharaf al-Hourani in Cairo contributed to this report.