Protesters hope to topple leader with final push

Protesters waved flags and sung the national anthem, emboldened after they repelling pro-regime attackers in two days of bloody street fighting.

In the wake of the violence, more detailed scenarios were also beginning to emerge for a transition to democratic rule after President Mubarak's nearly 30-year authoritarian reign.

Barack Obama's administration said it was discussing several possibilities with Cairo – including one for President Mubarak to leave office now and hand over power to a military-backed transitional administration.

Protesters in the square held up signs reading "Now!", massing around 100,000 in the largest gathering since the quarter-million who rallied on Tuesday.

In the afternoon, a group of President Mubarak's supporters gathered in a square several blocks away and tried to move on Tahrir, banging with sticks on metal fences to raise an intimidating clamour. But protesters throwing rocks pushed them back.

The 82-year-old president insists he will serve out the remaining seven months of his term to ensure a stable process.

But the Obama administration was in talks with top Egyptian officials about the possibility of President Mubarak immediately resigning and handing over to a military-backed transitional government headed by Vice President Omar Suleiman. Such a government would prepare the country for free and fair elections later this year, according to US officials.

The officials stressed that the United States isn't seeking to impose a solution on Egypt, but admitted the administration had made a judgment that President Mubarak has to go soon if there is to be a peaceful resolution.

Mr Suleiman has offered negotiations with all political forces, including the protest leaders and regime's top foe the Muslim Brotherhood, over constitutional changes needed to ensure a free vote ahead of September presidential elections to replace President Mubarak, who has promised not to run again.

Meanwhile, Europe's leaders delivered a warning to the Egyptian authorities to answer their people with "political reform, not repression".

An EU statement stopped short of calling on President Mubarak to step aside, but instead challenged the regime to honour the terms of a 150m-a-year EU "Association Agreement", under which Egypt is committed to push through political and economic reforms in return for trade concessions and financial aid.

The declaration emphasised the right to free and peaceful demonstration and said any attempt to restrict the free flow of information, including aggression and intimidation against journalists and "human rights defenders", was "unacceptable".

It also held out the offer of EU support for the transition processes towards "democratic governance".

The European message will now be backed up by a visit from EU foreign policy chief Baroness Ashton to both Tunisia – where the regime has stepped aside after a similar public backlash – and Egypt.