Egyptians vote on Saturday in the final round of a referendum on an Islamist-backed constitution that has fuelled weeks of sometimes bloody protests in the divided country but is likely to be approved.
Polling stations open at 8:00 am (0600 GMT) in the remaining 17 provinces that did not vote in last Saturday's first round of the referendum.
Hundreds of Egyptians clashed on Friday in the country's second largest city Alexandria in the latest violence between Islamists who back the charter and opponents who accuse them of overreaching.
The interior ministry said 62 people, among them 12 police conscripts, were injured and 12 protesters were arrested.
Some 250,000 police and soldiers will be deployed on Saturday to provide security at polling stations.
Last weekend's first round of the referendum exposed a deep rift in the country, with 57 percent of voters opting for the charter, according to unofficial tallies.
Analysts expect a majority of voters will accept the text in the second round also.
"Everything suggests the vote will go the way the Muslim Brotherhood wants," Hassan Nafaa, an analyst and commentator, wrote in the newspaper Al-Masri al-Youm.
Preliminary results compiled from returning officers are expected by early on Sunday. The electoral committee overseeing the referendum has not yet announced when it will declare the final official result.
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The constitution, drafted by an Islamist-dominated assembly boycotted by Christians and liberals, is at the heart of the power struggle between the Islamist president, Mohamed Morsi, and his secular-leaning opposition.
The main opposition group, the National Salvation Front, launched a last-minute campaign to vote down the charter after it failed to torpedo the referendum with mass rallies outside the presidential palace in Cairo.
Earlier in the month, confrontations turned deadly outside the presidential palace, with eight people killed and hundreds hurt.
Both the opposition coalition and civil society groups that monitored the vote allege fraud in the first round. The government's electoral committee denies the allegation.
If the constitution, which rights groups say limits religious freedoms and women's rights, is passed, Morsi will grant an Islamist-dominated senate full legislative powers until a new parliament is elected to replace the one annulled by Morsi's foes in a top court.
Analysts say the opposition will be emboldened even if it suffers a close defeat in the referendum, and will press ahead with rallies against the increasingly divisive president anyway.
They also said it was almost certain that adopting the new constitution would not end Egypt's political crisis.
The instability is also hurting the economy, which has limped along since the popular uprising that ousted the 30-year autocratic regime of Hosni Mubarak early last year.
The International Monetary Fund has put on hold a $4.8-billion loan Egypt needs to stave off a currency collapse, and Germany has indefinitely postponed a plan to forgive $316 million of Egypt's debt.
National Salvation Front chief Mohamed ElBaradei, a former UN atomic energy agency chief, warned in an online video that "the country is on the verge of bankruptcy."
But he said "a solution is still possible" if Morsi is prepared for "sincere dialogue" and allows a new constitution to be drafted through a more inclusive process.