CAIRO -- Mohammed Morsi, a twice-jailed member of the Muslim Brotherhood, was declared president of Egypt on Sunday, becoming this country’s first civilian, democratically elected leader, the region’s first Islamist president and the new official face of the 17-month-old uprising that has demanded, but not yet created, revolutionary change here.

The challenges ahead for Morsi are daunting. He is taking over a divided populace and sharing power with a military council that has governed Egypt directly or in the shadows since modern Egypt was created with the 1952 overthrow of the country’s monarchy. With no permanent constitution and the elected Parliament ordered dissolved 10 days ago, Morsi’s duties and powers are uncertain in a state where corruption and institutions established under the three-decade rule of Hosni Mubarak remain solidly in place,.

In his first television address, in a state media building he was once banned from, flanked by presidential guards who once served those who jailed him, Morsi delivered a message of national reconciliation. At one point he begged for unity. He praised nearly every major constituency and vowed to serve them all: the revolutionaries, the police, army, women, businessmen and religious leaders. He even called the Mubarak-appointed judiciary “independent.”

“I would not be standing here without the sacrifice of the martyrs,” Morsi said, a reference to those who had died during the 18 days of demonstrations that led to Mubarak’s resignation from the presidency. “I will serve all of Egypt. …The revolution continues until we achieve all our aims.”

And in a nod to the Egyptian peace deal with Israel, he said he was committed to “international agreements” and to peace.

Undeniably, Egypt had entered a new chapter as a nation with a history of autocratic rule that goes back thousands of years. Despite a week filled with conspiracies and fears of a rigged outcome, it appeared that the ruling military council had not obstructed the will of the people. Egypt had held a legitimate democratic election.

According to official election commission results, Morsi a 60-year-old engineer, garnered 13.2 million votes to Ahmed Shafik’s 12.3 million, a 52-48 percentage split that was almost identical to what Morsi had claimed just hours after the polls closed a week ago. But that didn’t stop the commission from leading up to the announcement with an hour-long explanation of its findings, including details on why the commission disqualified two votes for one of the candidates in a nation of 26 million voters. In the end, however, the difference between the results released by the Brotherhood in the hours after the vote and those unveiled Sunday showed just 5,000 fewer ballots for Morsi.

Morsi’s supporters were exuberant, thrilled not just by the results but also by the fact that they clearly had not been rigged.

“I knew Morsi won but we feared the military council would rig the results,” said Ahmed Hussein, 28, an accountant and fervent Morsi supporter who had spent two days in the square.

In Tahrir Square, the focus of the uprising that forced Mubarak from office, Morsi supporters erupted in cheers at exactly 4:29 p.m., when the results were announced.

The revelry was without restraint. People screamed, dropped to their knees in prayer and fired off fireworks, even though the sun was still up. Morsi supporters showered the crowds with water to fend off the scorching summer heat. Revelers remained well into the evening, in what looked likely to become an all-night street party.