The Egyptian military has drawn up a plan to suspend the Islamist-backed constitution, dissolve the Islamist-dominated parliament, and set up an interim administration if President Mohammed Morsi fails to reach a solution with his opponents, the state news agency says.
The report provides the first details of the road map the military has said it will implement if a deadline it set for tomorrow runs out with no solution.
A retired army general with close ties to the military confirmed the report.
Hossam Sweilam said a panel of experts would draft a new constitution and the interim administration would be a presidential council led by the Supreme Constitutional Court's chief justice and including the defence minister, representatives of political parties, youth groups, Al-Azhar Mosque and the Coptic Church.
Fearing a political-military implosion that could throw its most important Arab ally into chaos, the US has abandoned its hands-off approach, delivering pointed warnings to the three main players in the crisis.
US officials said today they are urging Mr Morsi to take immediate steps to address opposition grievances, telling the protesters to remain peaceful and reminding the army that a coup could have consequences for the massive American military aid package it currently receives.
The officials said Washington has stopped short of demanding that Mr Morsi take specific steps, but has instead offered strong suggestions, backed by billions of dollars in US aid, about what he should do to ease the tensions. Those include calling early elections, firing an unpopular prosecutor and expressing a willingness to explore constitutional change.
The army has been told that the 1.3 billion dollars in foreign military financing it receives each year from Washington could be jeopardised by a coup or the appearance of a coup.
Around the same time, Gen Martin Dempsey, chairman of the Joint Chiefs of Staff, called his Egyptian counterpart to point out that US law requires cuts in military assistance in most cases when a country's armed forces are involved in an unconstitutional change in government. Meanwhile, diplomats at the US Embassy in Cairo have been speaking to the opposition, the officials said.
In their conversation, Mr Obama "encouraged President Morsi to take steps to show that he is responsive to (opposition) concerns, and underscored that the current crisis can only be resolved through a political process," the White House said in a statement released before the president left Tanzania.
As Mr Obama flew back to Washington, some of his top national security advisers were meeting at the White House to plot a way forward. The conclusions of the so-called "deputies committee" meeting were not immediately clear.