Political factions both for and against Egypt's draft constitution agreed Sunday that it has likely been approved by those participating in the two-part referendum conducted Saturday and Dec. 15.

The Muslim Brotherhood, a supporter of the proposed constitution, said on Twitter: "Final results of phases 1&2 of referendum, and after adding expats votes: YES 64% (10,655,332) NO 36% (6,029,617)."

The National Salvation Front, an opponent of the proposed constitution, agreed it probably was passed by the voters, with one of its representatives telling Reuters, "They [the Islamists] are ruling the country, running the vote, and influencing the people, so what else could we expect?"

Challenges of the new constitution are anticipated.

Meanwhile, Egyptian Vice President Mahmoud Mekki announced his resignation during the referendum Saturday, thus becoming the latest high-ranking official to leave the administration of President Mohammed Morsi during the past month. Mekki, a former judge who was appointed vice president in August, said the "nature of politics" did not suit his professional background, according to BBC News.

Final results of the constitutional vote are expected to be announced Monday.