A new rally by nearly 100,000 protesters in central Cairo and behind-the-scenes diplomacy from the Obama administration piled more pressure on President Hosni Mubarak on Friday to make a swift exit from office and allow a temporary government to embark on an immediate path toward democracy.

Two days of wild clashes in central Cairo 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-old wave of protests, varying scenarios were being put forward by two opposing camps in Egypt and by the United States over how to usher the country into a post-Mubarak era after nearly 30 years of his authoritarian rule.

President Barack Obama's administration has made a judgment that Mubarak has to go soon if the crisis is to end peacefully, and it is in talks with Egyptian officials over the transition, according to U.S. officials.

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.