The appointment of liberal Egyptian politician Mohamed ElBaradei as interim prime minister hit a snag on Saturday, as the army-backed transitional authorities were under pressure to restore order after deadly Islamist protests.
State media and officials had said earlier that the 71-year-old Nobel Peace prizewinner and former UN nuclear agency chief would be named interim prime minister on Saturday evening.
But a presidential spokesman, speaking shortly before midnight, said there were several options for the job and the presidency had to take account of opposition to ElBaradei.
He mentioned no other candidates and added that there was no set date for the appointment of interim prime minister.
The Nour Party, Egypt's second biggest Islamist force, said it opposed ElBaradei and threatened to withdraw its support for the military-backed overthrow of President Mohamed Morsi on Wednesday, which was the trigger
for the bloody unrest.
A youth activist who met interim head of state Adli Mansour said the two issues were linked.
Losing Nour's backing would significantly weaken the position of the military, removing any Islamist support from the transition process, fiercely opposed by Morsi's Muslim Brotherhood.
Generals said they had intervened in response to huge popular demonstrations calling for Morsi to resign.
Raising the risk of further clashes, Morsi's Muslim Brotherhood, the dominant Islamist force in the Arab world's most populous nation, called for more protests on Sunday.
At least 35 people died in violence on Friday and Saturday, as pro- and anti-Morsi demonstrators fought running street battles in Cairo, Alexandria and beyond in violence that Egypt's powerful army was barely able to contain.
Tens of thousands of Brotherhood supporters took to the streets to protest against what they called a military coup, and clashes between them, security forces and anti-Morsi protesters left more than 30 people dead.
Within minutes of the news that ElBaradei would be named, a senior Brotherhood official said that the Islamist movement would reject his candidacy and any other measures implemented by the army-backed administration.
He described ElBaradei as "Washington's choice", a reference to suspicions among Brotherhood members of US complicity in Morsi's overthrow.
The Nour Party, which had endorsed the military's roadmap for a transitional phase leading to fresh elections, followed.
Those reactions underlined the challenges facing transitional powers as they seek to implement a military road map leading to fresh elections.
While the ouster of Egypt's first freely elected president was greeted with jubilation on streets crammed with millions of people, his many supporters feared a return to the suppression that the Islamists endured for decades under autocratic rulers.
The army has given few details and no time frame for elections, adding to political uncertainty at a time when many Egyptians fear that bloodshed could polarize society still further.
Morsi's dramatic removal and subsequent violence is the latest twist in a tumultuous two years since the fall of Hosni Mubarak in the Arab uprisings that swept the region.
At least 35 people died and more than 1,000 were wounded in violence on Friday and Saturday, with the army struggling to maintain order in Cairo, Alexandria and other cities and towns, where rival demonstrators fought street battles.
The most deadly clashes were in the Mediterranean city of Alexandria, where 14 people died and 200 were wounded.
In central Cairo, protesters clashed late into Friday night with stones, knives, petrol bombs and clubs as armored personnel carriers rumbled among them.
It took hours to restore calm on the Nile River bridges around the landmark Egyptian Museum. Anti-Morsi activists remained encamped in a suburb of the capital, but Cairo and others cities were relatively calm as darkness fell on Saturday.
While the Brotherhood has insisted it will not resort to violence, some radical Islamists have no such inhibitions.
On Saturday, a Coptic Christian priest was shot dead in Egypt's lawless North Sinai province
in what could be the first sectarian attack since Morsi's overthrow, raising concerns about the potential for further religious violence.
There were more attacks on army checkpoints in Sinai overnight and gunmen fired on a central security building in El Arish, security sources said.
A new Islamist group announced its formation in the Sinai peninsula adjoining Israel and the Gaza Strip, calling the army's removal of Morsi a declaration of war on their faith and threatening violence to impose Islamic law.
Ansar al-Shariah (Supporters of Islamic Law) in Egypt said it would gather arms and start training members, according to a statement on an online forum for Sinai militants recorded by SITE Monitoring.
The events of the last week have raised alarm among Egypt's allies in the West, including main aid donors the United States and the European Union, and in Israel, with which Egypt has had a US-backed peace treaty since 1979.
Newspapers quoted ElBaradei as saying that he expected Gulf Arab monarchies that were hostile to the Muslim Brotherhood's rule to offer financial support to the new authorities.
Only gas-rich Qatar provided substantial funds to Morsi's government, totalling $7 billion in loans and grants. Turkey and Libya also provided smaller loans and deposits.RISING TENSIONS
In one of the first outbreaks of violence on Friday, three protesters were shot dead outside the Republican Guard compound where Morsi is being held, security sources said. The army denied responsibility for the shootings. It was not clear whether other security forces were involved.
On Saturday, about 2,000 people gathered outside the barracks. A man with a loudspeaker told soldiers separated from protesters by razor wire not to open fire.
Thousands more Islamists braved the fierce midday sun at a sit-in outside a nearby mosque. Shawled women shook their heads and wept as an imam led prayers for "martyrs" of the violence.
At least 15 tanks were positioned on streets leading to the square outside the mosque, but they were farther away than on Friday, suggesting that the military was keen to ease tensions.
Elsewhere in Cairo, the retrial of former autocrat Mubarak
resumed at a snail's pace, in a bizarre coda to the past week's drama. The 85-year-old, who ruled Egypt for 30 years, is charged with conspiracy to murder hundreds of demonstrators in 2011.
The judge adjourned the case until Aug. 17. He said that he would continue to show proceedings live on state television, despite unhappiness among army commanders at seeing their former head of state and air force chief paraded in a courtroom cage.