Since its strong criticism of the violence against demonstrators, journalists and human rights leaders on Wednesday and Thursday, the administration has shifted its focus to emphasize the speed and substance of a dialogue. But while officials remained wary of pressing a specific plan, they said Mubarak's removal from the scene, either through resignation or some unspecified means of relinquishing power to Suleiman, was key to successful talks Saturday.
In addition to the question of what becomes of Mubarak, potential problems include a lack of recognized leaders who can speak authoritatively for the largely youthful protesters who have filled Tahrir Square, and uncertainty about whether they would accept a government under Suleiman.
"If Omar Suleiman was good for Egypt, then Mubarak would have never appointed him" vice president, said Abed el-Fateh Nabil, a 39-year-old activist who was in the square Friday. "We have been oppressed for 30 years, and we don't want anyone linked to Mubarak - not Suleiman or anyone else."
Still, some demonstrators suggested they would be open to having Suleiman play a central role in the transition - provided that role was temporary and that Mubarak was out of the picture.
"We can negotiate with Suleiman," said Ahmed Mohammed, a 23-year-old architect, as he waited his turn to enter Tahrir Square. "But first Mubarak has to leave."
Mohamed ElBaradei, the Nobel Peace laureate who has become one of the faces of the protest movement, said he respected Suleiman as a party to negotiations. ElBaradei said that a transitional government should be headed by a presidential council of two or three figures, including a military representative.
He said it could take a year for constitutional reforms to be put in place for new elections, a timetable that would make the current schedule of a September vote unrealistic.
There were other signs that the balance of power is shifting toward the demonstrators.
Arab League Secretary General Amr Moussa appeared for the first time in Tahrir Square on Friday and was given a rousing welcome by demonstrators, despite his earlier suggestion that they accept as a viable solution Mubarak's decision to stay on until September and not run for reelection.
Mohamed Rafah Tahtawy, spokesman for al-Azhar, the state-run university that is the nation's leading center of Sunni Islamic scholarship, announced he had resigned his post and joined the protests.
Osman Ibrahim, a retired Egyptian army general, said he took part in his first demonstration Friday. "I saw real Egyptians out there," said Ibrahim, 57. "It's not what we've been told by the Egyptian propaganda machine. These people are peaceful."
U.S. officials in Washington noted with approval the positive response by the demonstrators to an appearance in the square by Field Marshal Mohammed Hussein Tantawi, the Egyptian defense minister. Ostensibly there to talk with the troops, Tantawi stopped to chat with a group of protesters.
Although pro-government demonstrators gathered elsewhere in Cairo, they largely pulled back from positions surrounding the square. But government-orchestrated crackdowns on foreign journalists and human rights activists continued, with reporters facing attacks from pro-Mubarak forces and hotels turning reporters out of their rooms under what managers said was government pressure.
An unknown number of journalists and rights workers remained in custody Friday night. A group of foreign researchers for Human Rights Watch and Amnesty International, detained during a Thursday raid by security forces at the Hisham Mubarak Law Center in Cairo, were released. The government continued to hold their Egyptian colleagues.
In the most serious attack on the media here Friday, the al-Jazeera television network said its Cairo office had been stormed and burned by "gangs of thugs."
Despite the attacks and harassment, state television announced late Friday afternoon that foreign journalists were "most welcome" in Egypt.
DeYoung reported from Washington. Special correspondent Samuel Sockol in Cairo contributed to this report.