Egyptian police battled thousands of protesters outside President Mohamed Mursi's palace in Cairo prompting the Islamist leader to leave the building.
Officers fired teargas at up to 10,000 demonstrators angered by a decree to widen Mr Mursi powers and his drive to hold a hold a referendum on a new constitution.
Some broke through police lines around on Tuesday and protesters later surrounded the palace, with some climbing on gates at the rear to look down into the gardens.
At one point, people clambered onto a police armoured vehicle and waved flags, while riot police huddled nearby.
Presidency sources said the president left the palace as the crowds grew.
Facing the gravest crisis of his six-month-old tenure, the Islamist president has shown no sign of buckling under pressure, Reuters reports.
Despite the latest protests, there has been only a limited response to opposition calls for a mass campaign of civil disobedience.
Opposition groups have accused Mursi of making a dictatorial power grab to push through a constitution drafted by an assembly dominated by his supporters, with a referendum planned for Dec. 15.
They say the draft constitution does not reflect the interests of Egypt's liberals and other groups, an accusation dismissed by Islamists who insist it is a balanced document.