The parliamentary election that gets under way on Monday and Tuesday is the first step on the ruling army council's timetable toward a transfer to civilian rule, now promised for July.
Some Egyptians yearn for stability after a week of bloodshed that has killed 42 people and wounded over 2,000,preferring for now to let the generals run a nation whose prolonged political turmoil has thrust the economy deeper into crisis.
But the demonstrators want the council to make way for a civilian interim administration immediately. They reject its choice of 78-year-old Kamal Ganzouri to form the next cabinet.
Activists had called for a mass rally in Tahrir to pile pressure on the generals, and by mid-afternoon there were thousands in the square, hub of the unrest that toppled Mubarak.
Field Marshal Mohamed Hussein Tantawi, head of the council, said the army would ensure security at the polling booths.
"We are at a crossroads. There are only two routes, the success of elections leading Egypt toward safety or facing dangerous hurdles that we in the armed forces, as part of the Egyptian people, will not allow," he declared.
Abdel Moneim Aboul Futuh, an Islamist presidential candidate who opposes military rule, said: "The nation is larger than Field Marshal Tantawi and Lieutenant General Sami Enan and the military council. A government with revolutionary leadership must be formed to meet the demands of Tahrir Square."
State television quoted Tantawi as saying the army's role in the new constitution would be unchanged: to protect the nation.
The outgoing cabinet angered many Egyptians by floating proposals that would have given the army sweeping national security powers and protected it from civilian scrutiny.
The generals have received tacit support from Islamist parties eager that nothing should disrupt voting in the first of three rounds of an election in which they expect to do well.
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