Foreign envoys mounted new efforts on Tuesday to find a way out of the crippling political crisis sparked by the Egyptian army's ouster of Islamist president Mohamed Morsi.
Leading US Senators John McCain and Lindsey Graham called on Egypt's military-installed interim leaders to engage in an "inclusive" dialogue with Morsi supporters.
"Democracy is the only viable path to stability," said McCain, a former presidential candidate, calling for "an inclusive political process in which all Egyptians are free to participate."
Republicans McCain and Graham met earlier with army chief Abdel Fattah al-Sisi and other interim leaders amid an intense diplomatic push to end the stalemate.
As tensions mounted over the looming breakup of two protest camps maintained by Morsi loyalists, vice president Mohamed ElBaradei urged the Muslim Brotherhood to embrace a peaceful solution and called on Egyptian media to stop "demonising" the group.
The political crisis sparked by the military's July 3 overthrow of Morsi has paralysed the country and deepened social divisions.
Morsi loyalists say that the ouster of the country's first freely elected president violates democratic principles and that nothing short of his reinstatement will persuade them to leave the streets.
The interim leadership says there is no turning back on the army-drafted roadmap that provides for new elections in 2014.
A senior official told AFP that interim leaders were working on two tracks to end the crisis.
The first "is finding a political solution in which they would understand the reality and recognise that there has been change. In exchange, they get to participate in political life," the official said.
"As part of the package, they would ask their people to end their sit-ins," the official said.
The second option would be to disperse the protests "with as few losses as possible," the official said.
Since last week, a succession of foreign envoys has shuttled between the rival camps to try to prevent any repetition of the bloodshed at a pro-Morsi rally that left at least 82 people dead on July 27.
US Deputy Secretary of State William Burns, EU foreign policy supremo Catherine Ashton, EU envoy Bernardino Leon, Arab diplomats, an African delegation and German Foreign Minister Guido Westerwelle have all travelled to Cairo seeking to defuse the crisis.
Leon met Prime Minister Hazem al-Beblawi on Monday after he and Burns met the day before with the Brotherhood's number two, Khairat al-Shater, in prison.
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In Cairo, the senators called for the release of jailed Brotherhood leaders, including Morsi who has been formally remanded in custody on suspicion of offences committed when he escaped from prison during the 2011 revolt that toppled veteran president Hosni Mubarak.
"In a democracy, you have to talk to each other. It is impossible to talk to somebody in jail," Graham said.
"The judicial system will deal with this in the future. Jailing opposition is not the exercise of a legitimate power," he said.
On Tuesday, prosecutors ordered the detention of two of his aides for 15 days pending investigation into deadly clashes between supporters and opponents of the deposed president outside the Ittihadiya presidential palace last December.
Morsi's secretary Ahmed Abdel-Aati and his security advisor Ayman Hodhod join a string of Islamist leaders in jail.
The political impasse has slowed plans for a return to elected government.
"We have been so focused on (the protest camp at) Al-Rabaa al-Adawiya that we can't even concentrate on preparing the electoral process," a senior government official told AFP on Monday.
ElBaradei urged the Brotherhood not to gamble with the lives of pro-Morsi protesters for political gains and "join the peaceful solutions," in an interview with Al-Shorouk newspaper.
But the Brotherhood is standing its ground, with more scattered protests and marches in several parts of the capital on Tuesday.
"Only a political solution to restore continuity of constitutional legitimacy will end crisis," tweeted the group's spokesman Gehad al-Haddad.
A State Department spokeswoman said Burns and Leon visited Shater on Sunday, accompanied by the foreign ministers of US regional allies Qatar and the United Arab Emirates.
But Brotherhood spokesman Haddad said Shater gave the delegation a cold shoulder.
Authorities have promised demonstrators a safe exit and said an end to their protests would allow the Brotherhood's return to political life.
Interim foreign minister Fahmy insists the authorities have "no desire to use force if there is any other avenue that has not been exhausted."
More than 250 people have been killed since Morsi's ouster.