President of Egypt Abdel Fattah El Sisi addresses the United Nations General Assembly at UN headquarters, September 20, 2016 in New York City.

Egyptians vote this weekend on constitutional changes that will potentially allow President Abdel Fattah el-Sisi to stay in office until 2030 and bolster the role of Egypt's powerful military.

Sisi's supporters say the changes are necessary to give him more time to complete major development projects and economic reforms. Critics say they concentrate more powers in Sisi's hands and return Egypt to an unequivocally authoritarian model.

Egypt's 596-member parliament, dominated by Sisi's supporters, approved the amendments on Tuesday, voting by 531 to 22 in favor.

Some 55 million of Egypt's nearly 100 million population are eligible to cast votes in the referendum, which will be held over three days starting on Saturday.

While the changes are widely expected to pass, observers say the size of the turnout will be watched as a test of Sisi's popularity, which has been dented by economic austerity measures since 2016.

Opponents of the changes complained that they were being rushed through without proper public scrutiny.

"They are not giving us time to even organize a campaign to ask people to vote no," said Khaled Dawoud, a member of the opposition Civil Democratic Movement, which has rejected the changes.

"This is the final deathblow after all the ambitions we had after the 2011 revolution," said Dawoud, referring to the uprising that ousted veteran leader Hosni Mubarak. Dawoud said campaigning would take place online due to the lack of time.

Egyptian officials have said that Egyptians from all walks of life were given a chance to debate the amendments, and that all views were factored into the final proposals.