Witnesses say fighting between stone-throwing protesters began Friday near a mosque in Alexandria, the country's second largest city. Several cars were set on fire. There was no immediate word on injuries.
In Cairo and other cities, thousands of flag-waving activists turned out for rival rallies. Such gatherings have been generally "peaceful," killing 8 Egyptians in the last week.
The proposed constitution has the support of President Mohamed Morsi's Islamist Muslim Brotherhood and Salafist groups.
However, members of liberal, secular and Christian opposition note it will erode civil liberties because it boosts the role of Islamist Sharia law and does not mention women's rights.
An Islamist committee approved the document last month after minority liberal and Christian members walked out, stating they had been ignored by the Islamist body writing the constitution.
Last week, clashes between supporters and opponents left eight people dead and hundreds injured.
Polls open on Saturday in Cairo, Alexandria and a group of other provinces. The rest of the country will vote on December 22.
Egyptians living overseas began casting their ballots earlier this week.
Meanwhile, the United Nations Working Group has urged Egyptian officials to review the document to ensure that in conforms to international laws on equality and women's rights.
In a Friday statement, independent expert Kamala Chandrakirana said “key opportunities so far has been missed.” The group says the final draft of the constitution does not include adequate provisions to protect against gender discrimination. VoA.
The Muslim Brotherhood's Morsi came to power after Obama pressured his predecessor out of office and pressed for elections in Egypt before secularists could organize political powers. On 9/11/2012, Egyptian security forces delayed response led to the US Embassy being overrun, the US Flag desecrated, and the black flag of Al-Qaeda being raised over it. In neighboring Libya, the US Consulate in Benghazi was also overran, resulting in the deaths of the US Ambassador, and three Americans working for the US government.
Full text of proposed Islamist Constitution of Egypt