CAIRO (AP) -- The same chants used against Hosni Mubarak were turned against his successor Tuesday as more than 200,000 people packed Egypt's Tahrir Square in the biggest challenge yet to Islamist President Mohammed Morsi.
The massive, flag-waving throng protesting Morsi's assertion of near-absolute powers rivaled some of the largest crowds that helped drive Mubarak from office last year.
"The people want to bring down the regime!" and "erhal, erhal" -- Arabic for "leave, leave" -- rang out across the plaza, this time directed at Egypt's first freely elected president.
The protests were sparked by edicts Morsi issued last week that effectively neutralize the judiciary, the last branch of government he does not control. But they turned into a broader outpouring of anger against Morsi and his Muslim Brotherhood, which 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, with Morsi's opponents attacking Brotherhood offices, setting fire to at least one. Protesters and Brotherhood members pelted each other with stones and firebombs in the Nile Delta city of Mahalla el-Kobra, leaving at least 100 people injured.
"Power has exposed the Brotherhood. We discovered their true face," said Laila Salah, a housewife at the Tahrir protest who said she voted for Morsi in last summer's presidential election. After Mubarak, she said, Egyptians would no longer accept being ruled by 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 that could throw the nation into greater turmoil. Protest organizers have called for another mass rally Friday. If the Brotherhood responds with demonstrations of its own, as some of its leaders have hinted, it would raise the prospect of greater violence after a series of clashes between the two camps in recent days.
A tweet by the Brotherhood warned that if the opposition was able to bring out 200,000 to 300,000, "they should brace for millions in support" of Morsi.
Another flashpoint could come Sunday, when the constitutional court is to rule on whether to dissolve the assembly writing the new constitution, which is dominated by the Brotherhood and its Islamist allies. Morsi's edicts ban 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.
Morsi and his supporters say the decrees were necessary to prevent the judiciary from blocking the "revolution's goals" of a transition to democracy. The courts -- where many Mubarak-era judges still hold powerful posts -- have already disbanded the first post-Mubarak elected parliament, which was led by the Brotherhood. Now it could also take aim at the Islamist-led upper house of parliament.
Morsi's decrees ban the judiciary from doing so and grant his decisions immunity from judicial review. Morsi also gave himself sweeping powers to prevent threats to the revolution, stability or state institutions, which critics say are tantamount to emergency laws. These powers are to remain in effect until the constitution is approved and parliamentary elections are held, not likely before spring 2013.
Opponents say the decrees turn Morsi -- who narrowly won last summer's election with just over 50 percent of the vote -- into a new dictator, given that he holds not only executive but also legislative powers, after the lower house of parliament was dissolved.
Tuesday's turnout was an unprecedented show of strength by the mainly liberal and secular opposition, which has been divided and uncertain amid the rise to power of the Brotherhood over the past year. The crowds were of all stripes, including many first-time protesters.
"Suddenly Morsi is issuing laws and becoming the absolute ruler, holding all powers in his hands," said Mona Sadek, a 31-year-old engineering graduate who wears the Islamic veil, a hallmark of piety. "Our revolt against the decrees became a protest against the Brotherhood as well."