Egyptians go to the polls Tuesday and Wednesday to vote on a constitution written by the military-backed interim government.
The vote is widely seen as a referendum on a likely presidential run by the country's top general. In July, army chief Abdel Fattah al-Sisi deposed Mohammed Morsi, Egypt's first freely elected head of state.
The referendum will be the sixth nationwide vote since the 2011 ouster of longtime ruler Hosni Mubarak. It also comes just one year after a new constitution was signed into law by Mr. Morsi.
Analysts predict the constitutional referendum will easily pass.
Mr. Morsi's supporters have said they will stage massive demonstrations and boycott the vote.
The proposed constitution would strip out Islamist language in the existing document, give women greater rights and strengthen the power of the military.
In Washington, the U.S. State Department Monday expressed concern about reports that people campaigning for a 'no' vote have been arrested.
A spokeswoman said the United Sates is deeply troubled by reports that at least one individual was beaten during his arrest.
Egyptians living abroad already have voted on the new constitution.