WASHINGTON (AP) - Egyptian President Hosni Mubarak's announcement that he won't seek re-election came after President Barack Obama's special envoy told him the U.S. saw his presidency at an end and urged him to prepare for an orderly transition to real democracy, American officials said.

The message was delivered to Mubarak on Monday by Frank Wisner, a former U.S. ambassador to Egypt, according to two officials familiar with the envoy's mission. Obama dispatched Wisner to the country amid mounting anti-government protests and demands for the 82-year-old Mubarak to step down.

In a half-way concession to hundreds of thousands of protesters, Mubarak said late Tuesday in Egypt that he would serve out the rest of his term working to ensure a "peaceful transfer of power" and new rules on presidential elections. His message that he would not immediately leave was rebuffed by many in the throng of demonstrators in Cairo's main square.

The Obama administration didn't immediately comment on Mubarak's speech, though the president and his national security team were gathered in the White House Situation Room as it aired. The White House said Obama would deliver remarks on Egypt later Tuesday.

Wisner's message was disclosed as the Obama administration increased its outreach to Egyptian opposition groups determined to force their leader out. Perhaps most significantly the U.S. opened talks with a possible successor, Nobel peace laureate Mohamed ElBaradei.

The envoy's mission to speak to Mubarak signaled that after a week of balancing support for protesters and for America's close ally of three decades, U.S. leaders decided that long-term backing for the Egyptian president had become untenable.

Wisner and Mubarak are friends, and U.S. officials said the two had a back-and-forth discussion in which each provided the other with his perspective on developments.

Wisner expressed the U.S "view that his tenure as president is coming to a close," according to one official. A second official said Wisner had relayed Obama's assessment that Mubarak should not seek re-election in a scheduled September presidential vote.

Both officials spoke on condition of anonymity due to the delicacy of the matter.

On Capitol Hill, Sen. Patrick Leahy, D-Vt., said Mubarak must leave sooner than he plans because his government "has no credibility" to oversee a process toward democracy.

"His continued role in Egypt's transition is unrealistic," Leahy said in a statement.

Sen. John Kerry, D-Mass., was more conciliatory. "President Mubarak should now work with the military and civil society to establish an interim caretaker government," he said.

Even as the current U.S. envoy to Egypt, Margaret Scobey, spoke with ElBaradei, the escalating anti-government protests led the United States to order non-essential American personnel and their families to leave the country.

The U.S. said it had flown about 1,600 Americans out of Egypt since Monday. The State Department said Americans were struggling to reach Cairo's airport because roads were closed as a result of demonstrations. Some 60 U.S. citizens were expected to be flown out late Tuesday, with an additional 1,000 likely to be evacuated in coming days.

The Cairo airport is open and operating but the department warned that flights may be disrupted and that people should be prepared for lengthy waits. On Tuesday, it added Frankfurt, Germany, as a destination and the Egyptian cities of Aswan and Luxor as departure points.

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Associated Press writers Kimberly Dozier and Bradley Klapper contributed to this report.