CAIRO  President Hosni Mubarak appeared increasingly isolated on Friday, as hundreds of thousands of protesters returned to Tahrir Square and the Obama administration and some members of the Egyptian military and civilian elite pursued plans to nudge him from power.

The country’s newly named vice president, Omar Suleiman, and other top military leaders were discussing steps to limit Mr. Mubarak’s decision-making authority and possibly remove him from the presidential palace in Cairo  though not to strip him of his presidency immediately, Egyptian and American officials said. A transitional government headed by Mr. Suleiman would then negotiate with opposition figures to amend Egypt’s Constitution and begin a process of democratic changes.

Administration officials said that among the ideas that had been discussed were suggesting to Mr. Mubarak that he move to his home at Sharm el Sheik, the seaside resort, or that he embark on one of his annual medical leaves to Germany for an extended checkup. Such steps would provide him with a graceful exit and effectively remove him as the central political player, going partway toward addressing a central demand of protesters on the streets of Cairo.

Meanwhile, Mr. Suleiman and top military officers are being encouraged to have detailed discussions with opposition groups, conversations that would ultimately include how to open up the political system, establish term limits for the president and enshrine some key democratic principles ahead of elections scheduled for September.