(CNN) -- Fresh clashes broke out in Cairo Wednesday near Tahrir Square, as riot police fired tear gas and charged at Egyptian protesters angry about a move by President Mohamed Morsy to extend his powers.
Dozens of police officers -- backed by trucks firing tear gas -- advanced across Simon Boulevard Square, arresting many young people, some of whom were beaten by officers. Protesters continued to throw stones at police.
The latest clashes come after huge numbers of protesters swarmed into the square Tuesday night into Wednesday, hoping to revive a democratic groundswell that swept the country's former strongman from power nearly two years ago.
Observers suggested the crowds were the biggest seen since former President Hosni Mubarak was forced out early last year following days of street protests.
Demonstrators waved flags and banners, chanted slogans and called on their first freely elected leader to roll back last week's decree giving himself expanded presidential powers -- or resign. The crowd included many different Egyptian factions, including Western-style liberals, secularists, moderates and women's rights activists.
"I'm here because this is our country -- all of us," one woman told CNN. "It's not just for our president."
But Morsy showed no signs of backing down.
Egypt's Cabinet chief, Mohamed Refa'a al-Tahtawi, said there will be no retreat from the constitutional decree, state-run EGYNews reported. He reportedly stressed the president would not back down because his actions were motivated by democratic aims.
Mahmoud Ghozlan, a spokesman for the Muslim Brotherhood, Morsy's political movement, said Wednesday that it would stage nationwide protests Saturday in support of Morsy and his decree. The Muslim Brotherhood called off a planned "million man" protest Monday amid concerns over potential violence.
In a surprise move Wednesday, the council that has been drafting Egypt's new constitution -- a source of controversy -- said it was on the verge of concluding its work.
Sameh Ashour, head of the lawyers' syndicate and a former member of the council, told CNN a final draft of the constitution was expected to be completed Wednesday night and put to a vote Thursday.
Ashour said that only 55 members remain of the original 100-strong constituent assembly, since many have pulled out. The remaining members are all from the Islamic movement, be it Salafis or Muslim Brotherhood, he said.
"The Muslim Brotherhood are stealing the constitution, they are tailoring it according to their view after Coptic church representatives, civil movements, and revolutionary representatives withdrew," he said.
Dr. Ayman Nour, a former member of the constituent assembly, told CNN as he entered the assembly's meeting: "This cannot happen, it would be the biggest treason in Egypt's history."
Aly Hassan, a judicial analyst affiliated with the Ministry of Justice, said he was surprised the council was "rushing it after the president gave them an extra two months' extension to complete it in his latest constitutional decree. This could be a way for him to get out of this debacle without reversing his decree and decisions."
Morsy's November 22 decree said that judges can't overturn his decisions or interfere with the council. He also sacked the nation's top prosecutor.
Dr H.A. Hellyer, a non-resident fellow with the Brookings Institution think-tank, also suggested that the Muslim Brotherhood's efforts swiftly to push through a draft of the constitution could be an attempt to shift some of the focus away from Morsy.
Hellyer, who is currently in Cairo, considers that Morsy has "put himself in a tricky position" by issuing the edict because it has made it very difficult for him to compromise.
"I think his advisers are figuring out a way where he can climb down a little bit to defuse the situation without coming across as weak," he told CNN.
He believes the huge numbers turning out spontaneously to protest on Tuesday -- a working day -- reflect significant numbers of Egyptians from all backgrounds are unhappy over the president's assumption of new powers.
"If the protesters can keep up the momentum for another couple of days, they hit Friday, a day off. If they can do something quite intense on Friday, then that may push the presidency in an awkward position," he said.
The attempt to rush through a draft of the constitution may exacerbate the situation, Hellyer said.
However, despite critics' concerns over its drafting, the constitution would likely pass in a referendum because many Egyptians crave stability after months of uncertainty, he said. Islamist groups may also cast the decision in a religious light.
Once approved, it would be very difficult to protest against the referendum and its passage may be interpreted by Morsy's supporters as a vote of public approval for his presidency thus far, Hellyer added.
It is also unclear whether Morsy would then give up his additional powers immediately, or whether he will keep hold of them until a parliament is formed, he said.
There were no official crowd estimates for Tuesday night's demonstrations, but the square was packed as protesters clogged the roundabout and tents filled the grassy area in the middle. The rally lasted into early Wednesday, with some demonstrators singing and playing drums and guitars while others listened to speeches.
CNN iReporter Ahmed Raafat, who attended the protests in Cairo, said he saw hordes of people chanting as they headed to Tahrir Square.
"The atmosphere last night was great," he said. "There were people of all ages, men and women, people of different backgrounds ... I saw people who had never taken to the streets before."
Though the protest was mostly peaceful, at least one demonstrator died in early clashes with authorities ahead of Tuesday night's massive rally, the Ministry of Health said. The opposition Popular Alliance Party said the protester died after inhaling excessive amounts of tear gas, which police used in numerous scuffles with rock-throwing demonstrators on the side streets leading to the square.
Dr. Khaled al-Khatib, a Ministry of Health spokesman, said 290 people had been injured in Cairo since the clashes between police and protesters broke out late last week.
Another 120 people were injured in violence Tuesday night in the Nile Delta city of Mahalla, he said.
Police in Mahalla said demonstrators stormed the local headquarters of the Muslim Brotherhood, Interior Ministry spokesman Alla Mahmoud told CNN. Police also used tear gas to break up the melees and made numerous arrests, but the building was destroyed, Mahmoud said.
Ahmed al-Aguizi, a spokesman for the Freedom and Justice Party -- the Brotherhood's political arm -- said the anti-Morsy protesters carried knives, swords, clubs and guns and battled Brotherhood supporters for four hours.
Earlier this week, clashes in the northern city of Damanhour, where anti-Morsy protesters attacked local offices of the Muslim Brotherhood, also injured 20 people, al-Khatib said.
Critics have called Morsy's declaration last week an unprecedented power grab. And a statement Monday night regarding the scope of the decree did not dampen protesters' anger.
On Monday, Morsy's office clarified the edict, saying it only applied to "sovereign matters." Morsy "did not give himself judicial power" but did provide "immunity for his presidential decisions," said Jihad Haddad, a senior adviser in the Freedom and Justice Party.
Haddad added that "the president himself (is) not immune from judicial oversight," though it wasn't clear in what instances that would come into practice, or if there was anything preventing Morsy from issuing a new decree so this could not happen.
Protesters want to show that "the whole population of Egypt is against" Morsy and his backers, former Finance Minister Samir Radwan said.
Morsy and his Muslim Brotherhood supporters have defended the policy as necessary to support the fragile Arab Spring revolution that pushed Mubarak from power and led to the country's first free elections. On Tuesday, the Brotherhood's official Twitter feed dismissed the protests as underwhelming and said what it described as a low turnout indicated a "lack of support among Egyptians."
But Egyptian journalist Mona Eltahawy said the crowds have turned out to tell Morsy, "We are your checks and balances."
"We are the people who will keep you honest, right after you grabbed all of this power for yourself that has made you even more powerful than Mubarak, who we got rid of last year," Eltahawy told CNN. "So, the people are there to say, 'We might have elected you as president, but we did not elect a new dictator.' "
Eltahawy said Egypt's judiciary does need to be "cleansed" -- "but the way to help Egypt toward freedom is not by paving it with dictatorship."
In addition to outbursts on the street against Morsy's decree, Egypt's judges have reacted. All but seven of Egypt's 34 courts and 90% of its prosecutors went on strike Monday in protest, said Judge Mohamed al Zind of the Egyptian Judge's Club. He described Morsy's edict as "the most vicious ... attack on the judicial authority's independence."
Al Zind said Wednesday the Court of Cassation, the country's highest appeals court, had suspended its work until Morsy's decree is rescinded. He also announced that Sunday, the country's higher constitutional court would examine what he called the unconstitutional edict and would consider cases calling for the disbanding of the Shura Council, the upper house of parliament.
Morsy insists he's trying to protect Egypt's Arab Spring revolution, not accumulate unchecked power. His moves "cemented the process that would create the institutions that would limit his power, define the constitution and have parliamentary elections so that we can say this is a democracy," Haddad said.
Senior presidential aide Essam El-Erian called concerns about Morsy's edict overblown, blaming the protests on "counterrevolutionary forces" loyal to Mubarak's party. Polls show "an overwhelming majority supporting President Morsy and his decisions," Haddad said Monday.
But critics don't believe that.
Amr Hamzawy, a member of the now-dissolved parliament, said action is needed to prevent more "suffering" under a president with "sweeping powers," as Egypt had for 60 years under men like Mubarak, Anwar Sadat and Gamal Nasser.
"Morsy is the ... president who has sweeping executive (power), sweeping legislative (power) and ... puts himself above the judicial branch of government," said Hamzawy, founder of Egypt's Freedom Party. "That is a very dangerous mix, which can only lead to a dictatorship."
The rest of the world is watching, too.
Former U.S. diplomat Jamie Rubin said Morsy's edict "brings to mind all the fears that people in that part of the world have had about the Muslim Brotherhood when it comes to democracy."
The unrest also raises new concerns about stability in Egypt, which has gone through two years of protests and turmoil.
"The majority of the people are really suffering, and they were looking forward to some stability," said Radwan, the former finance minister, who served under Mubarak as well as in the government that followed him. "I'm afraid that this constitutional declaration has blown it up."