CAIRO — The power struggle between Egypt's Islamic and secularist forces intensified Wednesday, with some analysts warning of civil war and supporters of the Islamist government planning to march Saturday on a central square in Cairo where opponents have been holding a sit-in for more than a week.
Fears of violent street clashes between supporters and opponents of President Mohammed Morsi grew a day after more than 200,000 demonstrators crowded into Tahrir Square, the iconic scene of last year's Arab Spring protest, to denounce the president for decrees he issued last week that put him above any oversight, including the judiciary.
Judges in the country's appellate courts joined the protest Wednesday by announcing a strike against any further legal business until Mr. Morsi rescinds his decree.
Meanwhile, the country's highest judicial panel, the Supreme Constitutional Court, announced a direct challenge to Mr. Morsi. It said it will rule Sunday on whether to dissolve a 100-member assembly writing a new constitution, which is dominated by Mr. Morsi's Muslim Brotherhood and other Islamist allies.
"We are fearful that, for the first time, the prospect of a civil war is now on the agenda," said Khaled Fahmy, a history professor at the American University in Cairo.
"I have always said, 'No, I don't think this can happen.' [Now], I feel that this can very well happen."
The constitution will define how Egypt's government functions. Secular Egyptians are concerned that Islamists are imposing a constitution that grants the president too much power and could limit freedom of speech and the rights of women and minorities.
"Egypt is lost for good, ruined for good," said Mona El-Ashry, 39, a pharmacist. "Today, the Muslim Brotherhood decided to occupy Egypt. The Muslim Brothers do not treat Egyptians as one family. They impose everything on the people and will never leave the throne."
Rushing to pass the constitution
Islamists continued their attempts to pass the constitution despite the withdrawal over the past few weeks of liberal, leftist and Coptic Christian members of the constitutional assembly. The assembly is pushing to finish a draft of the legal charter by Thursday.
The head of the assembly, Hossam al-Gheriany, urged secular members to "come back and finish the discussion on Thursday."
Still, his attempts to assuage opposition concerns are unlikely to succeed, given the tense mood in Cairo, analysts say.
"The feeling is at the moment that certainly among the opposition, none of the checks and balances that they want will be strong enough," said David Hartwell, an analyst at Jane's Defense Weekly.
Others say the decision to put the constitution to a vote Thursday reflects confidence in Mr. Morsi's camp that Islamic forces will win a subsequent referendum early next year. That vote would confirm the popular legitimacy of the draft constitution.
"They feel that they will have enough votes to pass it, and I believe them," Mr. Fahmy said.
The assembly made its decision to vote on the constitution as Egypt's top appeals court, the Court of Cassation, went on strike.
The court has declared that it will cease working until Mr. Morsi reverses a constitutional declaration he made last week that broadened his powers and exempted him from judicial oversight.
The Supreme Constitutional Court has denied it is working to undermine Mr. Morsi's government and rejected charges that it favored the regime of Hosni Mubarak, who was ousted last year.
Many secularist Egyptians are backing the judges, but Islamists remain skeptical.
"If I were Morsi, I would expel them all," said 39-year-old Radwa Amer, clad in a headscarf. "[The judges] are biased toward a certain regime – the past one. They want everything to stay as it was."
As the institutional game plays out in the constitutional assembly, the streets of Cairo are full of angry demonstrators.
Police fired tear gas into Tahrir Square, where several hundred protesters were gathered hours after an opposition rally Tuesday at the symbolic heart of the Arab Spring.
Uniting the opposition
Opponents of the Egyptian president have been gathering in the square since last week. The demonstration has drawn prominent opponents of the Egyptian president, such as Mohamed ElBaradei, a former head of the International Atomic Energy Agency.
Protesters say Mr. Morsi, in just four months since taking office, has united Egypt's disorganized opposition.
"Most of them are new to the square," said Sabrine Abu Sabaa, a veteran opposition activist who has been going to Tahrir Square since protests began Friday.
"It really shows Morsi is really brilliant, that in four months he could make them unite regardless of their ideology."
Mr. Morsi's Muslim Brotherhood and other Islamists responded to opposition rallies in Cairo on Wednesday by announcing a "Million Man March" to be held Saturday to prove the depth of support for the president, party officials said.
"The liberals don't like that Islamists are [putting their stamp on] the constitution," Mr. Amer said. "But democracy is rule by the majority. Islam is coming to this country. It has to. It is our religion."
With both sides out in the streets and politicians and the judiciary polarized, the loyalties of Egypt's armed forces will be tested in the days to come, analysts said. It was the army's withdrawal of support that brought down Mubarak in February 2011.
"The state of polarization and tension will increase. The question is whether there will be direct confrontations and whether the army will interfere again," Mr. Fahmy said.
The escalating tension in Cairo reflects an institutional vacuum in Egypt, with several institutions trying to gain dominance.
"You have a president without an elected parliament, a judiciary which is sort of a Mubarak hangover, and the military which is sort of hanging in the background," said Mr. Hartwell, from Jane's Weekly.
"You get the feeling that they are jousting among themselves, trying to test the limits of where each other's power lies."
Charles McPhedran reported from Berlin. Sarah Lynch in Cairo contributed to this article, which is based in part on wire service reports.