President Barack Obama is prodding Egyptian President Hosni Mubarak to quickly loosen his grip on power, sternly telling the world that the longtime leader's transition from the presidency “must begin now.”

Obama spoke at the White House not long after Mubarak, a key U.S. ally in the volatile Middle East, announced Tuesday evening that he would not seek re-election in balloting now set for September. But Mubarak said he would stay in office until then to oversee a political changeover that would mark the end of his authoritarian 30-year reign.
Mubarak's concession not to seek office again, until recently nearly unthinkable, was angrily rejected by throngs of protesters in Cairo who are fed up with poverty and corruption and want Mubarak to step down immediately. They have vowed to stay in the streets until he does.

It also did not appear to satisfy Obama. After days of scrambling in the White House over how to react to the enormous and unanticipated protest movement enveloping America's top Arab ally, the president came down unmistakably on the side of the demonstrators, though he stopped well short of echoing their demand for Mubarak's immediate resignation.

After speaking to Mubarak on the phone for half an hour, the president delivered brief remarks in which he offered high praise for the protesters and the Egyptian army, which apparently has sided with the protesters. But Obama did not welcome or even directly mention Mubarak's announcement that he would not stand for re-election.

“It is not the role of any other country to determine Egypt's leaders. Only the Egyptian people can do that,” Obama said. “What is clear — and what I indicated tonight to President Mubarak — is my belief that an orderly transition must be meaningful, it must be peaceful, and it must begin now.”

Meanwhile, thousands of supporters and opponents of Mubarak battled in Cairo's main square Wednesday, raining stones, bottles and firebombs on each other in scenes of uncontrolled violence as soldiers stood by without intervening. Government backers galloped in on horses and camels, only to be dragged to the ground and beaten bloody.

At the front line, next to the famed Egyptian Museum at the edge of Tahrir Square, pro-government demonstrators blanketed the rooftops of nearby buildings, dumping bricks and firebombs onto the crowd below — in the process setting a tree ablaze inside the museum grounds.

On the street below, the two sides crouched behind abandoned trucks and hurled chunks of concrete and bottles at one another and some government supporters waved machetes.

Bloodied anti-government protesters were taken to makeshift clinics in mosques and alleyways nearby and some pleaded for protection from soldiers stationed at the square, who refused. Soldiers did nothing to stop the violence beyond firing an occasional shot in the air and no uniformed police were in sight.

“Hosni has opened the door for these thugs to attack us,” one man with a loudspeaker shouted to the crowds during the fighting.

The clashes marked a dangerous new phase in Egypt's upheaval — the first significant violence between supporters of the two camps in more than a week of anti-government protests. Clashes began, first in the port city of Alexandria just hours after Mubarak rejected protesters' demands he step down immediately and insisted he would serve out the remaining seven months of his term.

That speech marked an abrupt shift in the deteriorating crisis. A military spokesman appeared on state TV Wednesday and asked the protesters to disperse so life in Egypt could get back to normal. That was a major turn in the attitude of the army, which, for the past few days, allowed protests to swell to their largest yet on Tuesday, when a quarter-million peacefully packed into Tahrir Square.

Also, the regime for the first time Wednesday began to rally supporters in significant numbers to demand an end to the unprecedented protest movement calling for Mubarak's removal.

Some 20,000 pro-government demonstrators held an angry but mostly peaceful rally across the Nile River from Tahrir, saying Mubarak's concessions were enough and demanding protests end.