Egypt's main opposition coalition is calling for new protests against a draft constitution that is set to go before a second round of voting on Saturday.
The National Salvation Front is urging Egyptians to demonstrate Tuesday against the proposed charter, which opponents say will erode civil liberties because it boosts the role of Islamic law and does not mention women's rights.
An Islamist-dominated assembly drafted the document, and supporters say its passage is an important step in Egypt's transition to democracy.
President Mohamed Morsi claimed victory in the first round of voting last week. The opposition says widespread violations marred the vote.
A group of top judges said Monday it will not oversee the second round of voting. The State Council of Judges joined many members of the country's judiciary, who boycotted the initial round of the referendum.
The first round was held in 10 of Egypt's 27 regions, including the two main cities of Cairo and Alexandria. The second round will be held in Egypt's remaining provinces, most of which are rural and religiously conservative. The measure needs a simple majority of the vote to pass.
The Muslim Brotherhood, backers of Morsi, said 56 percent of voters approved the referendum in the first round.
Unofficial tallies showed a low turnout with about one-third of the 26 million eligible voters participating. Egypt's election commission put turnout at 51 percent when voters elected Mr. Morsi in a June runoff election.
Meanwhile, Egypt's prosecutor general Talaat Abdullah submitted his resignation Monday after hundreds of public prosecutors staged a sit-in to protest his appointment.
President Morsi named Abdullah to the post after issuing a decree on November 22 putting himself above judicial oversight. Prosecutors say only the Supreme Judicial Council can nominate a prosecutor general, so as to ensure a separation of powers.
If Abdullah's resignation is accepted, it will be a blow to the Islamist president who has been in a power struggle with the judiciary since last month.
Germany says it has postponed debt relief for Egypt because of concerns that the government is sliding toward dictatorship.
Morsi's actions last month were hailed by his Islamist supporters, but they also triggered nationwide outrage among liberals and non-Muslims. The opposition called his decree a "coup," and the judges described it as a direct attack on the independence of the judiciary.