President Mohamed Morsi called on Egyptians on Saturday to vote in a December 15 referendum on the controversial draft constitution at the heart of a political crisis, amid mass Islamist rallies in Cairo.
Morsi made the announcement following a ceremony where he received a copy of the charter from the head of the Islamist-dominated constituent assembly, boycotted by liberals and Christians, that adopted it the day before.
Hundreds of thousands of Islamists rallied from early on Saturday in support of Morsi's new expanded powers and the contested charter. The document has taken centre stage in the country's worst political crisis since his election in June.
Crowds flooded the squares and large avenues near Cairo University, led by members of the Muslim Brotherhood, on whose ticket Morsi ran for office, and by hardline Salafists, causing traffic jams in the capital.
On Friday, opponents of the draft constitutions had massed in Tahrir Square, demonstrating the country's widening polarisation that has set largely Islamist forces against secular-leaning opponents.
"We want this phase to end. We want a constitution," one protester said on Saturday. "If people don't like the constitution, let them say so through the ballot boxes."
Others chanted: "The people want the implementation of God's law."
"We are here to support the decisions of Dr Mohamed Morsi; we support him because those decisions were a part of the revolutionary demands," said Hend Abdellateef.
Veiled women ululated among the crowd, sprinkled with Egyptian and Saudi flags and posters of Morsi. Banners read: "Together (with Morsi) to save the revolution".
"There are people who want instability," said Khaled, one of the demonstrators, referring to anti-Morsi protesters. "There needs to be a constitution for there to be stability."
Pro-Morsi protests were also staged in the Mediterranean city of Alexandria and the central Egyptian province of Assiut.
The crisis was sparked when Morsi issued a decree on November 22 giving himself sweeping powers and placing his decisions beyond judicial review. That move provoked mass protests and a judges' strike.
His decree prevented the top legal body the Supreme Constitutional Court from potentially dissolving the Islamist-run constituent assembly, in a ruling it was to make on Sunday on the body's legality.
After Morsi's speech hundreds of his supporters, chanting and waving flags, gathered outside the Supreme Constitutional Court in south Cairo ahead of Sunday's verdict. Hundreds more marched along the banks of the Nile towards the courthouse.
The Muslim Brotherhood and their supporters have branded the opposition enemies of the revolution that toppled longtime dictator Hosni Mubarak in 2011.
Across the Nile River, hundreds of protesters camping out in Tahrir Square since Morsi issued a decree assuming sweeping powers were joined by more demonstrators throughout the day.
The National Rescue Front -- a coalition of opponents led by Mohamed ElBaradei, the former UN nuclear watchdog chief; ex-Arab League chief Amr Mussa; and former presidential candidate Hamdeen Sabbahi -- has called on opponents of the decree to maintain the pressure.
It called on Egyptians to "reject the illegitimate" decree and the "void" draft constitution, and stressed the public's right "to use any peaceful method to protest including a general strike and civil disobedience."
Joe Stork of Human Rights Watch said: "Rushing through a draft while serious concerns about key rights protections remain unaddressed will create huge problems."
Amnesty International said the draft "raises concerns about Egypt's commitment to human rights treaties," specifically ignoring "the rights of women (and) restricting freedom of expression in the name of religion."
In an interview broadcast on Thursday night, Morsi again stressed that his new powers would expire once the constitution was ratified, a point Islamist supporters have repeatedly made in his favour.
In 2011, the Brotherhood and the secular-leaning opposition stood side by side in Tahrir Square as they fought to bring down Mubarak and his regime.
But since Mubarak's downfall in February 2011, the Islamist movement has been accused of monopolising power.