CAIRO (AP) — In front of tens of thousands of cheering supporters, Egypt’s first Islamist and civilian president-elect vowed Saturday that nobody can take away his authority and symbolically read an oath of office in Cairo’s Tahrir Square on the eve of his official inauguration.

Mohammed Morsi’s strongly worded speech was a show of defiance as he gears up for a power struggle with the country’s ruling generals who passed a constitutional declaration taking over major presidential powers in the days before election results were announced.

Mohammed Morsi Vows to Fight for Power in Egypt

Egypt's President-elect Mohammed Morsi is guarded by presidential security as he leaves Friday prayers at Al-Azhar mosque, in Cairo, Egypt, Friday, June 29, 2012. Mohammed Morsi was declared Egypt's first freely elected president in modern history on Sunday, June 24, 2012. (AP Photo/Amr Nabil)

“Everybody is hearing me now. The government, the military and the police … No power above this power,” he said as the crowd roared.

Morsi promised to reject any efforts to take away the power of the people, telling his supporters, “you are the source of legitimacy and whoever is protected by anyone else will lose.”

Morsi, the 60-year-old U.S. trained engineer who initially was put forward as a back-up candidate for the Muslim Brotherhood, addressed the crowd with a booming voice as he was flanked by several security guards.

At one point he opened his jacket to show the crowd he wasn’t wearing a bulletproof vest, saying he “fears no one but God.”

Many protesters had called for Morsi to hold his swearing-in ceremony in the square, the epicenter of mass protests that ousted his predecessor Hosni Mubarak, but the military generals ordered the swearing-in to be held in front of a high court, in the absence of a parliament. The ceremony was scheduled to be held Saturday.

Mohammed Morsi Vows to Fight for Power in Egypt

Muslim Brotherhood presidential candidate Mohamed Morsi speaks during a press conference in Cairo in June 22, 2012 where he warned against any tampering with the election result, after a win was also claimed by his rival ex-premier Ahmed Shafiq. (AFP/GettyImages)

However, he read an informal oath during his speech to the delight of the crowd. Many chanted “We love you Morsi” and “Oh marshal tell the truth, Morsi is your president, or not,” referring to the head of the ruling military panel Field Marshal Hussein Tantawi.

The ruling generals have promised to transfer power to an elected president by Sunday. But they also have given themselves sweeping powers that undercut the authority of the president. The constitutional declaration — issued days before the winner of a runoff vote was announced — also designated the generals the country’s legislature in place of the disbanded parliament.

The disbanding of parliament forced Morsi to take his oath in front of the Constitutional Court, which ruled against the parliament and whose judges were appointed by Mubarak.

He also addressed popular demands, vowing to release Omar Abdel-Rahman, the blind sheik jailed in the U.S. for a plot to blow up New York landmarks as well as detained Egyptian protesters facing military tribunals.