There are fears that mounting popular fury against Morsi and the once-banned Brotherhood, the godfather of radical Islamist movements across the Muslim world, could trigger another uprising like the 2011 revolution that toppled the dictator Hosni Mubarak and led to Morsi's rise to power in June 2012.
Opposition protests are scheduled for Cairo, Alexandria and other Egyptian cities. Morsi's Islamist loyalists plan to stage a major rally in Cairo Friday with sit-ins slated to run into next week.
The prospect of a clash amid the current tension, and the dashed expectations of change unleashed in 2011, is widely expected -- particularly since Morsi, whose administration has accomplished little to improve conditions for Egypt's 82 million people, has clearly decided to confront his opponents.
Clashes between the Brotherhood and its liberal and leftist opponents are commonplace these days.
Two people were killed and 200 injured in clashes Wednesday between rival factions in the Nile Delta town of Mansoura, north of Cairo.
Assem Abdel Maged, leader of the extremist al-Gamma al-Islamiya, a U.S.-designated terrorist group that slaughtered 58 tourists at Luxor in 1997, had declared: "The Islamists will meet violence with violence on June 30."
"Given the opposition's growing rage and the Brotherhood's increasingly confrontational stance, the upcoming nationwide protests are unlikely to end well," warned analyst Eric Trager of the Washington Institute for Near East Policy.
"The anti-Brotherhood backlash ... is the product of mounting popular frustrations regarding the organization's failed governance of Egypt during Morsi's first year in office."
Egypt has been in a state of chaos since the revolution against Mubarak, unable to establish a functioning democracy. There seems no end in sight to the turmoil in a country that for long was the center of the Arab world.
A new civil war -- added to the conflicts raging in Iraq, Syria and Yemen, and simmering in Lebanon, Turkey, Jordan, Libya, Algeria, all linked by a hard-line Islamist network -- would plunge the Middle East into ever deeper turmoil and uncertainty.
Morsi's opponents accuse the Brotherhood of seeking to monopolize power just as Mubarak did during his 32-year rule, and turn Egypt into an Islamic dictatorship. They have rejected Morsi's calls for a national dialogue, saying these are nothing more than empty, photo-opportunity gestures.
In a televised address Wednesday, Morsi admitted: "I have made mistakes on a number of issues."
He promised to introduce "radical and quick" reforms in state institutions.
During his 2-1/2-hour speech to cabinet ministers, senior Brotherhood officials and supporters of its political arm, the Freedom and Justice Party, Morsi declared "enemies of Egypt have not spared an effort in trying to sabotage the democratic experience."
He did not identify these enemies but it was a clear reference to members of Mubarak's corruption-riddled regime.
"There are those who are under the illusion that the clock can go back and they can bring back the state of repression, monopolies, corruption and injustice," Morsi said.
He warned that unless compromise was reached "political polarization and conflict has reached a stage that threatens ... to put the whole nation in a state of paralysis and chaos."
The army, which has largely stayed out of politics since Mubarak's downfall in February 2011, is reluctant to get involved. But this week it warned the ruling Islamists and their secular opponents that it might have to step in if serious violence breaks out Sunday.
The opposition has called on Egypt's 310,000-strong army to support them. But Gen. Abdel Fattah al Sisi, the defense minister appointed by Morsi, declared the military, the power behind Mubarak's 32-year rule, had a "moral and patriotic duty" to Egypt's 82 million people to intervene to prevent "civil war," "sectarian strife," or "the collapse of state institutions."
Nevertheless, there are concerns that security officials of the former regime may seek to provoke violence Sunday to force the military to take control.
The opposition, built around cadres of young activists who see a secular democracy in which Muslims and Coptic Christians can co-exist, says it has collected 15 million signatures in a campaign dubbed "Tamarod," or rebellion, demanding early presidential elections.