By Griff Witte - Washington Post Staff Writer

CAIRO - As pro-democracy demonstrators vowed to bring 1 million people to the streets of Egypt, President Hosni Mubarak offered a gesture of conciliation on Monday, directing his new vice president to begin talks with his opponents about changes to the country’s constitution.

But Mubarak offered no sign that he is intending to step down, leaving questions about whether the decentralized and leaderless movement that has swept Egypt over the past week can muster the force necessary to topple this nation’s deeply entrenched establishment.

Protesters have already accomplished far more than anyone here thought possible, forcing Mubarak to call the army to the streets and focusing global attention on the president’s autocratic 30-year reign. But unlike other successful democratic uprisings, this one lacks charismatic personalities and any clear agenda beyond ousting Mubarak and holding elections to choose a successor.

Appearing on state-run television to discuss his new role, Vice President Omar Suleiman offered no details about the scope or timing of any talks. In an olive branch of its own, the military promised to guarantee "freedom of expression’’ during a march planned for Tuesday, saying it recognizes "the legitimacy of the people’s demands."

Opposition leaders, including Mohamed ElBaradei, a Nobel Peace laureate and democracy advocate, have signaled that they are ready for such a dialogue. Demonstrators, however, say that the opposition leaders do not represent them and that they will be satisfied only with Mubarak’s ouster.

The movement that rose up seemingly out of nowhere last week to pose the greatest challenge yet to the 82-year-old president has no name, no symbols and no formal infrastructure. Although some students and others are involved in organizing its direction, they deny being its leaders.

Protesters say the absence of a specific platform or a single dynamic figure has been critical to their success, allowing them to tap into Egyptians’ widespread contempt for Mubarak without allowing the movement to become riven by factions.

"There are many talented people who could govern this country. As long as it’s not Mubarak and his circle," said Ahmed Allam, a 31-year-old accountant, reflecting a sentiment that is broadly shared among demonstrators.

Allam was among the tens of thousands who jammed Tahrir Square on Monday night as Cairo’s central plaza took on a joyful atmosphere before the mass mobilization planned for Tuesday. Demonstrators waved Egyptian flags and chanted relentlessly against Mubarak. In an indication that they intend to stay, they distributed large quantities of food and water, established first-aid stations and even set up satellite television service so they could keep up with news from outside the plaza.

Egypt’s organized political opposition was caught off guard by the past week’s protests and has struggled to catch up. The outlawed Muslim Brotherhood, the country’s largest opposition group, acknowledges that it has played only a marginal role.

ElBaradei was picked by opposition leaders on Sunday to lead any possible negotiations with the government. But when he spoke to demonstrators later that evening, many in the crowd ignored him.

Still, ElBaradei, 68, could be a crucial figure if the offer by Suleiman, who is also Mubarak’s longtime intelligence chief, proves genuine. ElBaradei has called for Mubarak to step aside, and has said he has the "political and popular support" necessary to form a unity government while the nation transitions to a democracy.