Egyptian authorities battled to save President Hosni Mubarak's regime with a series of concessions and promises to protesters, but realities on the streets of Cairo may be outrunning his capacity for change.
Under increasingly strong US pressure to make "an orderly transition" to democracy and opposition calls for 1 million people to flood the streets of Egyptian cities on Tuesday, Mubarak's newly appointed and first-ever vice president said he had been ordered to engage with "political forces" for constitutional and legislative reforms.
Mubarak's military, the bulwark of Egyptian society, joined in, promising not to open fire on demonstrators and accepting "the legitimacy of the people's demands."
Those concessions, stunning in the context of Mubarak's iron-fisted 30-year tenure, suggest he knows his time at the top may be growing short.
Mubarak has ruled Egypt, after succeeding the assassinated Anwar Sadat, from an impregnable political fortress, banning virtually all opposition and relying on the ready and quick brutality of his interior ministry and its police.
Yet, as much as the United States may applaud the appearance of a more democratic Egypt, the transition from Mubarak to an unknown future in the volatile Middle East is weighted with anxiety for the United States and Israel. Many fear an opening to a far more fertile landscape for radical Islam.
Mubarak's departure would have a dramatic effect throughout the region. The former fighter pilot's once-unchallenged hold had put him at the pinnacle of power as the leader of the most populous Arab country, the critical crossroads between the Middle East and North Africa.
Under Mubarak, Egypt has been a steadfast US ally and a point of stability in an explosive region.
Even so, the momentum toward upheaval in the way Egypt is governed appeared to grow Monday when the State Department said a retired senior diplomat, former Ambassador to Egypt Frank Wisner, was in Cairo and would meet Egyptian officials to urge them to embrace broad economic and political changes leading toward free and fair elections.
The unprecedented week of unrest that began as a decentralized eruption of anger largely by grassroots activists appeared to be coalescing under a unified political leadership. About 30 representatives from various opposition groups met Monday to work out a joint stance and issue the call for an escalation of protests Tuesday.
A further meeting was set to decide on making prominent reform advocate Mohamed ElBaradei the movement spokesman.
ElBaradei is a Nobel Peace laureate and former chief of the International Atomic Energy Agency, the United Nation's nuclear watchdog. He was frequently at odds with President George W Bush's administration over Saddam Hussein's nuclear weapons ambitions in the lead-up to the 2003 U.S. invasion of Iraq.
But unity, if it occurs, may be short-lived among the various protesters, who have little in common beyond the demand that Mubarak leave power. There could be deep divisions between young secular activists and the Muslim Brotherhood, which wants to form an Islamist state. The more secular are deeply suspicious that the Brotherhood aims to co-opt what they contend is a spontaneous, popular movement.
American officials have suggested they have similar fears. Washington worries an ascendant Muslim Brotherhood could walk away from Egypt's 30-year peace treaty with Israel.
Arab leaders and monarchs elsewhere in the Mideast, particularly in Saudi Arabia and Jordan, both long-time US allies, know they rule over restive populations that share many of the aspirations now driving protesters through the streets of Egyptian cities.
While President Barack Obama chose Cairo early in his administration to deliver a speech to Arabs and Muslims, promising friendship but demanding more democracy, little must he have expected the uproar that would later grip Egypt. And the Mubarak regime is engulfed in crisis only weeks after a similar explosion of popular anger forced Tunisia's long-ruling dictator to flee to Saudi Arabia.
The wave of dissatisfaction on the Arab streets is proving the biggest test of Obama's foreign policy dexterity. Given the potential threat to US energy supplies from the oil-rich region, it could also confound his attempts to put the US economy back on a sound footing.