Egyptians were being asked on Saturday to vote on constitutional amendments that would allow President Abdel-Fattah el-Sissi to stay in power until 2030.
The three-day voting period for the nationwide referendum starts at 9am (0700 GMT) on Saturday on proposed changes that would also further enshrine the military’s role in politics.
Parliament, packed with el-Sissi supporters, overwhelmingly approved the amendments on Tuesday.
The proposed changes are seen by critics as another step back toward authoritarianism.
The referendum comes eight years after a pro-democracy uprising ended autocrat Hosni Mubarak’s three-decade rule, and nearly six years after el-Sissi led a popular military overthrow of the country’s first freely elected but divisive Islamist president, Mohammed Morsi.
The vote comes as authorities waged an unprecedented crackdown on dissent in recent years, arresting thousands of people mostly Islamists but also prominent secular activists and rolling back freedoms won in 2011.