Egypt's reform leader Mohamed ElBaradei is pulling out of the country's presidential race to protest at the military's failure to put the country on the path to democracy.
The 69-year-old Nobel laureate, who has been seen as a driving force behind the movement that forced former President Hosni Mubarak to step down, said in a statement that the conditions for a fair presidential election were not in place.
ElBaradei said the military rulers who took over from Mubarak have governed "as if no revolution took place and no regime has fallen".
His decision to pull out of the race just days before the one-year anniversary of the January 25 uprising reflects the dilemma in which Egypt's revolutionary movement finds itself.
They are caught between a military they say is trying to hold on to power and a newly-elected parliament dominated by the Islamist Muslim Brotherhood which revolutionaries fear will give the generals what they want and radicalise society.
The military rulers have said they will transfer power after presidential elections, to be held before the end of June. But many expect a fierce struggle over the military's future privileges.
ElBaradei, who said he intends to work with youth groups from outside the system to push for democracy and social justice, echoed fears that the military would not give up power to future elected rulers.
"I reviewed the best ways to serve the goals of the revolution in light of this reality, and I found none within the official framework, including (running for) the presidency," he said.
"I had said from the start that my conscience will not allow me to run for president or any official position unless there is a real democratic framework, that upholds the essence of democracy and not only its form."