CAIRO — Thousands of Islamists flowed into Cairo's Tahrir Square today to hear Egypt's president-elect make his first public speech since declaring victory in a clear bid to rally popular support as he faces a struggle for power with the ruling generals.

Mohammed Morsi of the Muslim Brotherhood is the first Islamist and the first civilian to win the presidency, a job held for nearly three decades by Hosni Mubarak who was ousted by an uprising last year.

But he is already facing a serious challenge after the Mubarak-era military rulers who oversee the transition took a series of decisions undermining the powers of his office before his swearing-in, which was scheduled for Saturday.

His visit to Tahrir is also a nod to the protesters who supported his bid for leadership in a bitter campaign that pitted him against Mubarak's last prime minister Ahmed Shafiq.

Many protesters have called for Morsi to take the oath of office in the square, the epicenter of mass protests against Mubarak and later the continued military rule, but the ceremony was scheduled to be Saturday before a high court.

His appearance in Tahrir a day before the official ceremony is clearly a nod to the calls for a popular oath.