CAIRO (AP) -- Giant crowds of protesters packed Cairo's Tahrir Square and marched in other cities Friday vowing to stop a draft constitution that Islamist allies of President Mohammed Morsi approved hours earlier in a rushed, all-night session without the participation of liberals and Christians. Anger at Morsi even spilled over into a mosque where the Islamist president joined weekly Friday prayers. In his sermon, the mosque's preacher compared Morsi to Islam's Prophet Muhammad, saying the prophet had enjoyed vast powers as leader, giving a precedent for the same to happen now. "No to tyranny!" congregants chanted, interrupting the cleric. Morsi took to the podium and told the worshippers that he too objected to the language of the sheik and that one-man rule contradicts Islam. Crowds of protesters marched from several locations in Cairo, converging in central Tahrir Square for the opposition's second mass rally in a week against Morsi. They chanted, "Constitution: Void!" and "The people want to bring down the regime" as fireworks went off. The crowd appeared comparable in size to the more than 200,000 anti-Morsi protesters who thronged Tahrir on Tuesday. Tens of thousands more marched Friday in Alexandria and other cities. In contrast to the largely leaderless uprising by youth activists against autocrat Hosni Mubarak last year, a more energized, cohesive leadership has started to emerge in the new campaign against Morsi, Egypt's first freely elected president. It is made up of a number of prominent liberal, secular and moderate Islamist politicians, notably reform advocate Mohamed ElBaradei. "We are determined to continue with all peaceful means, whatever it takes to defend our legitimate rights," ElBaradei told the Tahrir crowd, saying the draft constitution must be voided. His ally, senior opposition leader Hamdeen Sabbahi, vowed protests would go on until "we topple the constitution." "The revolution is back ... We shall be victorious," said Sabbahi, a liberal politician who came in a surprisingly close third in last summer's presidential election. "We are united against the oppressive regime." The protests were sparked by the president's decrees a week ago granting himself sweeping powers and neutralizing the judiciary, the last check on his authority. The edicts tapped into a feeling among many Egyptians that Morsi and the Muslim Brotherhood, from which he hails, are using their election victories to monopolize power and set up a new one-party state, nearly two years after the fall of autocrat Hosni Mubarak. But the sudden adoption of a draft constitution by the Islamist-dominated assembly tasked with producing the document throws the confrontation into a new phase. The draft must now be put to a nationwide referendum for public approval, likely to be held in mid-December. Morsi is expected on Saturday to announce the date. He says his new powers are in effect until the referendum passes. The opposition appeared determined to launch a street campaign aimed at blocking the document from coming to a referendum. They are also counting on a revolt by the judiciary, where opposition to Morsi's edicts runs strong. The Supreme Constitutional Court is to rule on Sunday whether to dissolve the constitutional assembly. If it does so, the effect on the draft already adopted by the assembly is unclear. In part it may be a question of whose legitimacy is stronger and whose public support is larger. If the charter does come to a referendum, the opposition is faced with the choice of boycotting in protest or trying to rally the public to vote to reject the draft. In every scenario, Egypt's most polarizing and volatile crisis since Mubarak's ouster is likely to deepen. The past week, clashes between Morsi's supporters and opponents left two dead and hundreds wounded and raised fears of further chaos. The Brotherhood and other Islamists plan their own massive rally backing Morsi on Saturday. Already on Friday, Brotherhood activists were passing out fliers calling for the public to come out and "support Islamic law." A number of Muslim clerics in Friday sermons in the southern city of Assiut called the president's opponents "thugs" and "enemies of God and Islam."