Two days of wild clashes between protesters and regime supporters that killed 11 people this week seemed to have pushed the United States to the conclusion that an Egypt with Mubarak at the helm is potentially more unstable than one without him.
For the first time in the 11-day wave of protests, varying scenarios were being put forward by two opposing camps in Egypt and by the United States on how to usher the country into a post-Mubarak era after nearly 30 years of his authoritarian rule.
President Barack Obama said that discussions have begun in Egypt on a turnover of the government and he called for "a transition period that begins now."
"We want to see this moment of turmoil turned into a moment of opportunity," Obama said in Washington. He did not explicitly call for Mubarak to step down immediately, but U.S. officials said the administration has made a judgment that Mubarak has to go soon if the crisis is to end peacefully.
Under one U.S. proposal, the 82-year-old Mubarak would step down and hand power to a military-backed temporary government headed by his newly appointed vice president, Omar Suleiman, the officials said, speaking on condition of anonymity to discuss the sensitive talks. The government would prepare for free and fair elections later this year.
That would mesh in some ways with the demands of the protesters. But one significant difference was the timetable.
Nobel Peace laureate Mohamed ElBaradei, one of the leaders of the protesters, criticized the government's plan to reform the constitution within five months and hold presidential elections in September, saying that was too rushed.
It would take a full year under a transitional government to sufficiently loosen the ruling party's entrenched monopoly on politics before a truly democratic election can be held, ElBaradei said. The ruling party has squeezed out almost all rivals with a grip solidified in vote fraud, election rules tilted in its favor, widespread patronage, emergency laws and domination of the media.
"People are not stupid ... This is not really a genuine desire to go for reform," ElBaradei said of the government's timeframe. He said Mubarak must "hear the clear voice coming from the people and leave in dignity."
Mubarak has staunchly refused to step down until elections in September, and his prime minister said Friday that stance is "unlikely" to change.
The protesters have vowed to continue their rallies until Mubarak goes, and they seemed flush with a sense of victory and recharged determination after repelling pro-regime rioters who attacked Tahrir Square on Wednesday, sparking 48 hours of mayhem and pitched battles.
Nearly 100,000 people packed the downtown plaza, whose name means "Liberation," in a protest dubbed the "Friday of departure" in hopes it would be the day Mubarak goes. It was the biggest showing since a quarter-million people rallied Tuesday.
Crowds that included families with children flowed over bridges across the Nile into Tahrir, a sign the movement was not intimidated by the violence of the previous two days. In that fighting, pro-Mubarak combatants, some on horses and camels, hurled concrete, metal bars and firebombs, and unleashed barrages of automatic gunfire, but were eventually driven away.
The ruling National Democratic Party, accused by protesters of organizing the attack, denied any role, but called on its supporters to "adhere to a truce and not enter confrontations with others." Protesters say the regime organized the assault by police in civilian clothes and paid thugs.
Suleiman and Prime Minister Ahmed Shafiq promised no action would be taken against the protest camp. A curfew in place for a week but widely ignored was eased Friday, to run from 7 p.m. to 6 a.m.
The Tahrir clashes brought the death toll since Jan. 25 to 109 people. Among them was a reporter from a state-run newspaper who was shot by a sniper last week while photographing clashes from his balcony and died Friday - the first journalist death in the crisis.
Unlike those earlier protests, the atmosphere Friday in Tahrir Square was relaxed. Many brought fresh bread, water and fruit, and long lines formed at tables where tea was handed out. Celebrities of Egyptian cinema and TV joined the march, including Sherihan, a screen beauty from the 1980s and early 1990s.
In the morning, Defense Minister Hussein Tantawi visited the square, the highest government figure to do so. He reviewed the troops stationed there and mingled with protesters, trying to convince them that most of their demands have been met and they should go home.
Arab League chief Amr Moussa also came to the square in what appeared to be a trial balloon for running for Egypt's presidency.
His convoy was greeted with chants of "We want you as president, we want you as president!" Moussa, previously a foreign minister under Mubarak, has an elder statesman appeal, boosted by his tough rhetoric against Israel.
Asked by France's Europe 1 radio if he would consider a role in the transitional government or an eventual presidential run, Moussa replied, "Why say no?"
In a sign of cracks in some key regime pillars, Mohammed Rafat al-Tahtawi, the spokesman of Al-Azhar Mosque, the country's pre-eminent Islamic institution, announced on Al-Jazeera that he had resigned and was joining the protesters. Al-Azhar is a major source of support for Mubarak, giving his rule religious backing, and its top sheik has called for protesters to go home.
In a sign that Egypt's most powerful institution was sanctioning the demonstration, soldiers at the entrances to Tahrir checked IDs to keep out police in civilian clothes and ruling party members. The protesters themselves set up another ring of checks inside the army cordon.
Demonstrators held up signs reading "Now!" At one point, the crowd seemed to be a field of waving Egyptian red-black-and-white flags. Thousands prostrated themselves in the noon Muslim prayers then - immediately after uttering the concluding "God's peace and blessings be upon you" - they launched into chants of "Leave! Leave! Leave!" A man was lifted in his wheelchair over the heads of the crowd and he pumped his arms in the air.
The pro-government rioters of the past two days largely disappeared. In the afternoon, small groups of Mubarak supporters tried to move on the square, banging with sticks on metal fences to raise an intimidating clamor. But protesters throwing rocks pushed them back. More than two dozen people were injured, most of them slightly.
On the other side of Cairo, dozens of regime supporters carrying machetes and sticks set up an impromptu checkpoint on the ring-road highway encircling the city of 18 million. They stopped cars, asking for IDs, apparently trying to root out people heading to Tahrir to join the protest. One of the armed men wore a sign reading, "We are sorry, Mr. President."
Many of the protesters involved in the fighting still wore tattered bandages. Around the square were makeshift clinics, set up in the entrances of stores, including a KFC restaurant. Above one was the sign of an interlocking crescent and cross, the signs of Islam and Christianity.
Despite the call for Mubarak's immediate departure, Prime Minister Shafiq told Al-Arabiya that was "unlikely."
"Mubarak's remaining as president is a source of security for the nation," he said.
Trying to launch the transition with Mubarak in place, Vice President Suleiman has offered talks with all political forces over constitutional changes to ensure a free vote. Mubarak has said he will not run for re-election.
Suleiman said the invitation goes out to protest leaders and the regime's top foe, the Muslim Brotherhood. That was significant, suggesting the banned fundamentalist group could be allowed an open political role in the post-Mubarak era.
But so far the protest factions have stuck to their condition that Mubarak step down before any negotiations on the constitution.
ElBaradei's comments reflected a widely held view among protesters that unless Mubarak goes and a broader transitional government is put in place, the regime will try to limit reforms to preserve its hold on power. They dismiss as illegitimate Shafiq's government, appointed by Mubarak soon after the protests erupted.
Suleiman has talked of changing the constitution to ensure fair supervision of elections, loosen restrictions on who can run for president and impose a term limit for the presidency.
ElBaradei and other protest leaders demand more. They want an end to an emergency law that gives security forces near unlimited powers and demand greater freedom to form political parties. Currently, any new party effectively needs approval by Mubarak's ruling party. As a result, the existing opposition parties are largely shells with little popular support or organization.
Suleiman has not mentioned either issue. He served as intelligence chief and Mubarak's top aide until being elevated to vice president, and is mistrusted by some as a regime figure, but others have spoken him as an acceptable interim president.
ElBaradei said he respects Suleiman as someone to negotiate with over the transition.
ElBaradei said he was consulting with lawyers and experts to draw up a temporary constitution. He called for a transitional government headed by a presidential council of two or three figures, including a military representative. It would hold power for a year while a permanent constitution is drawn up, then elections could take place.
Still, he underlined that the protest movement is not seeking "retribution" or a purge of the ruling party, only a more level playing field. "Not everyone who worked with the regime should be eliminated," he said.
AP correspondents Hamza Hendawi, Sarah El Deeb and Maggie Michael contributed to this report.