On Saturday, new clashed broke out in the southern city of Assiut. Morsi opponents and members of the Muslim Brotherhood swung sticks and threw stones at each other outside the offices of the Brotherhood's political party, leaving at least seven injured.
ElBaradei and a six other prominent liberal leaders have announced the formation of a National Salvation Front aimed at rallying all non-Islamist groups together to force Morsi to rescind his edicts.
The National Salvation Front leadership includes several who ran against Morsi in this year's presidential race — Hamdeen Sabahi, who finished a close third, former foreign minister Amr Moussa and moderate Islamist Abdel-Moneim Aboul-Fotouh. ElBaradei says the group is also pushing for the creation of a new constitutional assembly and a unity government.
ElBaradei said it would be a long process to persuade Morsi that he "cannot get away with murder."
"There is no middle ground, no dialogue before he rescinds this declaration. There is no room for dialogue until then."
The grouping seems to represent a newly assertive political foray by ElBaradei, the former chief of the U.N. nuclear watchdog agency. ElBaradei returned to Egypt in the year before Mubarak's fall, speaking out against his rule, and was influential with many of the youth groups that launched the anti-Mubarak revolution.
But since Mubarak's fall, he has been criticized by some as too Westernized, elite and Hamlet-ish, reluctant to fully assert himself as an opposition leader.
The Brotherhood's Freedom and Justice political party, once headed by Morsi, said Saturday in a statement that the president's decision protects the revolution against former regime figures who have tried to erode elected institutions and were threatening to dissolve the constitutional assembly.
The Brotherhood warned in another statement that there were forces trying to overthrow the elected president in order to return to power. It said Morsi has a mandate to lead, having defeated one of Mubarak's former prime ministers this summer in a closely contested election.
Morsi's edicts also removed Abdel-Meguid Mahmoud, the prosecutor general first appointed by Mubarak, who many Egyptians accused of not prosecuting former regime figures strongly enough.
Speaking to a gathering of judges cheering support for him at the high court building in Cairo, Mahmoud warned of a "vicious campaign" against state institutions. He also said judicial authorities are looking into the legality of the decision to remove him — setting up a Catch-22 of legitimacy, since under Morsi's decree, the courts cannot overturn any of his decisions.
"I thank you for your support of judicial independence," he told the judges.
"Morsi will have to reverse his decision to avoid the anger of the people," said Ahmed Badrawy, a labor ministry employee protesting at the courthouse. "We do not want to have an Iranian system here," he added, referring to fears that hardcore Islamists may try to turn Egypt into a theocracy.
Several hundred protesters remained in Cairo's Tahrir Square Saturday, where a number of tents have been erected in a sit-in following nearly a week of clashes with riot police.
Brian Rohan contributed to this report from Cairo.