Despite the discord in the streets and critics' concerns about the constitution's drafting, Hellyer predicts it will probably pass in a referendum because many Egyptians crave stability.

The Muslim Brotherhood has called for its own demonstration Saturday, in what would be the biggest public show of support for Morsy since he issued his controversial edict.

They will be joined on the streets Saturday by more opposition protests, if all goes to plan.

"If the (anti-Morsy) protesters can keep up the momentum for another couple of days ... that may push the presidency in an awkward position," Hellyer said.

Analysis: Morsy makes his move