CAIRO — More than 200,000 people thronged Cairo’s central Tahrir Square, protesting against Egypt’s Islamist president Tuesday in an opposition show of strength, as the standoff over Mohammed Morsi’s assertion of near absolute powers escalated into the biggest challenge yet to his and the Muslim Brotherhood’s rule.

The massive, flag-waving, chanting crowd in the iconic plaza rivaled the size of some of the large protests of last year’s uprising that drove autocrat Hosni Mubarak from office. The same chants used against Mubarak were now turned against Egypt’s first freely elected leader.

“The people want to bring down the regime,” and “erhal, erhal” — Arabic for “leave, leave,” rang across the square.

Protests in Tahrir and several other cities Tuesday were sparked by edicts issued by Morsi last week that effectively neutralized the judiciary, the last branch of government he does not control. But it turned into a broader outpouring of anger against Morsi and the Muslim Brotherhood. Opponents say have used election victories to monopolize power, squeeze out rivals, and dictate a new, Islamist constitution, while doing little to solve Egypt’s mounting economic and security woes.

Clashes broke out in several cities as Morsi opponents tried to attack offices of the Brotherhood. At least 100 people were injured when protesters and Brotherhood members protecting their office pelted each other with stones and firebombs in the Nile Delta city of Mahalla el-Kobra.

“Power has exposed the Brotherhood. We discovered their true face,” said Laila Salah, a housewife in the Tahrir protest who said she voted for Morsi in this summer’s presidential election. After Mubarak, she said, Egyptians would no longer consent to an autocrat.

“It’s like a wife whose husband was beating her and then she divorces him and becomes free,” she said. “If she remarries she’ll never accept another day of abuse.”

Gehad el-Haddad, a senior adviser to the Brotherhood and its political party, said Morsi would not back down on his edicts. “We are not rescinding the declaration,” he told The Associated Press.

That sets the stage for a drawn-out battle between the two sides that could throw the nation into greater turmoil. Protest organizers on a stage in the square called for another mass rally on Friday. If the Brotherhood responds with mass rallies of its own, as some of its leaders have hinted, it would raise the prospect of greater violence.

A tweet by the Brotherhood warned that if the opposition was able to bring out 200,000-300,000 “they should brace for millions in support” of Morsi.

Another flashpoint could come Sunday, when the constitutional court is due to rule on whether to dissolve the assembly writing the new constitution, which is dominated by the Brotherhood and Islamist allies. Morsi’s edicts explicitly banned the courts from disbanding the panel. If the court defies him and rules anyway, it would be a direct challenge that could spill over into the streets.

“Then we are in the face of the challenge between the supreme court and the presidency,” said Nasser Amin, head of the Arab Center for the Independence of the Judiciary and the Legal Profession. “We are about to enter a serious conflict” on both the legal and street level, he said.