The lines at polling places around Cairo seemed far smaller Tuesday than they did during the previous constitutional referendum, in December 2012, and reports from around the country suggested smaller crowds as well. But the vote will take place over two days, and voters often wait to visit the polls until after they get off work, so the ultimate turnout was impossible to forecast. (Egyptian state radio reported long lines and big crowds everywhere.)

About a third of the electorate turned out to vote on the last charter, which passed by a ratio of about two to one nationwide but was rejected by a majority in Cairo. The referendum had followed a noisy debate in which anti-Islamist politicians, judges, diplomats and most of the privately owned media attacked it for opening a door to future religious restrictions on individual liberties.

The new charter retains the main clause of the current one, stipulating that the principles of Islamic law are the wellspring of Egyptian jurisprudence. It removes a more controversial clause that had sought to constrain the way judges interpreted those principles, defining them according to the broad outlines of mainstream Sunni Muslim scholarship.

Even though the Muslim Brotherhood opposes the charter, the ultraconservative Islamist party Al Nour is still supporting it, accepting its fidelity to Islamic law.