WASHINGTON (Reuters) - President Barack Obama was poised on Friday to welcome Egyptian President Hosni Mubarak's decision to step down but Washington now faces deep uncertainty and big challenges in dealing with Egypt's potentially volatile transition of power.
Obama, who had struggled to calibrate his response to a popular uprising against Mubarak's long authoritarian rule, was due to deliver a statement at 1:30 p.m. EST after Mubarak handed power over to the army.
Washington had walked a fine line since the demonstrations began, endorsing the democratic aspirations of the protesters but trying not to openly abandon a long-time ally or encourage an abrupt upheaval that could spill over into other parts of the oil-rich Middle East.
Obama, who has repeatedly pressed for an orderly transition to democracy, now faces the challenge of backing broad political reform in the Arab world's most populous country while keeping Islamists from ending up with enough power to undermine U.S. interests in the region.
U.S. officials will now do everything possible to keep intact close ties with the powerful Egyptian army, which relies heavily on U.S. aid and is seen as the key to keeping the situation from descending into chaos.
"The president was informed of President Mubarak's decision to step down during a meeting in the Oval Office. He then watched TV coverage of the scene in Cairo for several minutes in the outer Oval (office)," White House spokesman Tommy Vietor said.
U.S. officials have said repeatedly they are entering uncharted waters and see a long period of uncertainty and volatility.
"This is very good news for Obama given that he and his administration so publicly staked out a position that change should happen now. But it is only the start of a process," said Brian Katulis, Middle East expert at the Center for American Progress in Washington and an informal adviser to the White House.
"This is going to be a very long and protracted process over negotiated power. The political opposition had one unifying demand, which was get rid of Mubarak. Now the real work has to begin," he said..
(Editing by Eric Beech)