CAIRO (AP) ― Faced with an unprecedented strike by the courts and massive opposition protests, Egypt’s Islamist president is not backing down in the showdown over decrees granting him near-absolute powers.

Activists warn that his actions threaten a “second revolution,’’ but Mohammed Morsi faces a different situation than his ousted predecessor, Hosni Mubarak: He was democratically elected and enjoys the support of the nation’s most powerful political movement.

Already, Morsi is rushing the work of an Islamist-dominated constitutional assembly at the heart of the power struggle, with a draft of the charter expected as early as Thursday, despite a walkout by liberal and Christian members that has raised questions about the panel’s legitimacy.

The next step would be for Morsi to call a nationwide referendum on the document. If adopted, parliamentary elections would be held by the spring.

Wednesday brought a last-minute scramble to seize the momentum over Egypt’s political transition. Morsi’s camp announced that his Muslim Brotherhood and other Islamists will stage a massive rally in Cairo’s Tahrir Square, the plaza where more than 200,000 opposition supporters gathered a day earlier.

The Islamists’ choice of the square for Saturday’s rally raises the possibility of clashes. Several hundred Morsi opponents are camped out there, and another group is fighting the police on a nearby street.

“It is tantamount to a declaration of war,” said liberal politician Mustafa al-Naggar, speaking on the private Al-Tahrir TV station.

Morsi remains adamant that his decrees, which place him above oversight of any kind, including by the courts, are in the interest of the nation’s transition to democratic rule.

Backing down may not be an option for the 60-year-old U.S.-educated engineer.

Doing so would significantly weaken him and the Brotherhood at a time when their image has been battered by widespread charges that they are too preoccupied with tightening their grip on power to effectively tackle the country’s many pressing problems.

Morsi’s pride is also a key factor in a country where most people look to their leader as an invincible figure.

He may not be ready to stomach another public humiliation after backing down twice since taking office in June. His attempt to reinstate parliament’s Islamist-dominated lower chamber after it was disbanded in July by the Supreme Constitutional Court was overturned by that same court. Last month, Morsi was forced to reinstate the country’s top prosecutor just days after firing him when the judiciary ruled it was not within his powers to do so.

Among Morsi’s first acts after seizing near-absolute powers last week was to fire the prosecutor again.

Unlike last year’s anti-Mubarak uprising, calls for Morsi’s ouster have so far been restricted to zealous chants by protesters, with the opposition focusing its campaign on demands that he rescind his decrees, disband the constitutional panel and replace it with a more inclusive one, and fire the Cabinet of Prime Minister Hesham Kandil.