CAIRO -- Egypt's new president moved to assert his authority and regain control of the streets Saturday even as his Islamist opponents declared his powers illegitimate and issued blood oaths to restore Mohammed Morsi, whose ouster by the military has led to dueling protests and pitched street battles between rival sides.
But underscoring the sharp divisions facing the untested leader, Adly Mansour, his office said it was naming Mohamed ElBaradei, one of Morsi's top critics, as interim prime minister but later backtracked on the decision.
Mansour's spokesman Ahmed el-Musalamani denied that the appointment of the Nobel Peace laureate was ever certain. However, reporters gathered at the presidential palace were ushered into a room where they were told by an official to wait for the president, who would arrive shortly to announce ElBaradei's appointment.
A senior opposition official, Munir Fakhry Abdelnur, told The Associated Press that the reversal was because the ultraconservative Salafi el-Nour party objected to ElBaradei's appointment and mediation was under way.
Tensions were high as tens of thousands of Morsi supporters rallied for a third day near a mosque in a Cairo neighborhood that has traditionally been a stronghold of Islamists, chanting slogans against Wednesday's toppling of the country's first democratically elected president by Gen. Abdel-Fattah el-Sissi. The general has denied the military staged a coup, saying he was acting on the wishes of millions of Egyptians protesting the ex-Islamist leader.
But no major violence was reported Saturday as all sides regrouped after a night of clashes between Morsi's supporters and opponents.
Setting up another showdown, the youth opposition group behind the series of mass protests that led to Morsi's ouster called on Egyptians to take to the streets on Sunday to show support for the new order.
Mansour, 67, the former chief justice of the country's constitutional court who was installed by the military as an interim leader, met earlier Saturday with el-Sissi and Interior Minister Mohammed Ibrahim, who is in charge of the police. He also met separately with the three young leaders of Tamarod, or Rebel, which organized the massive opposition protests that began June 30, the anniversary of Morsi's inauguration.
Morsi's Muslim Brotherhood, meanwhile, has promised to boycott the political process, saying the military maneuver was a coup that overturned a democratically elected government.
Morsi, a U.S.-trained engineer who was widely accused by critics of monopolizing power for himself and his Muslim Brotherhood as well as his failure to implement democratic and economic reforms, remained under detention in an undisclosed location.
The 2011 uprising that ousted autocrat Hosni Mubarak opened the way for the political rise of the Muslim Brotherhood, which was long suppressed by Mubarak's Western-backed regime, and Morsi was elected last year by a narrow margin. The fundamentalist movement swiftly rejected earlier news of ElBaradei's appointment, calling the 71-year-old former UN nuclear negotiator a remnant of Mubarak's regime.