"If the protesters can keep up the momentum for another couple of days, they hit Friday, a day off. If they can do something quite intense on Friday, then that may push the presidency in an awkward position," Hellyer said.

It is also unclear whether Morsy would then give up his additional powers immediately, or whether he will keep hold of them until a parliament is formed, he said.

Analysis: Morsy makes his move

The Muslim Brotherhood has attempted to rally support for Morsy during the row. It dismissed Tuesday's protests and plans nationwide protests Saturday in support of the president and his decree, spokesman Mahmoud Ghozlan said Wednesday. The Brotherhood called off a planned "million man" protest Monday amid concerns over potential violence.

Meanwhile, Egypt's judges have responded to the decrees by shutting down courts around the country. All but seven of Egypt's 34 courts and 90% of its prosecutors went on strike Monday in protest, said Judge Mohamed al Zind of the Egyptian Judge's Club. He described Morsy's edict as "the most vicious ... attack on the judicial authority's independence."

Al Zind said Wednesday the Court of Cassation, the country's highest appeals court, had suspended its work until Morsy's decree is rescinded. He also announced that Sunday, the country's higher constitutional court would examine what he called the unconstitutional edict and would consider cases calling for the disbanding of the Shura Council, the upper house of parliament.