Kenya's election commission named Uhuru Kenyatta the winner of the country's presidential election with 50.07 percent on Saturday, but his opponent alleged multiple failures in the vote and said Kenya's democracy was on trial.

Supporters of Kenyatta — a man accused by an international court of helping to orchestrate the vicious violence that marred the nation's last vote — flooded the streets, celebrating in a parade of red, the campaign's color.

Less than two hours after the official announcement, Kenyatta's top opponent, Prime Minister Raila Odinga, said the election process experienced multiple failures and that he would petition the Supreme Court.

Odinga called for calm and asked Kenyans to love one another but said he would not concede because he did not believe he had lost.

"I have stated that nothing could have pleased me more if I had lost fairly," he said, adding: "We have highlighted so many irregularities with the tallying process."

Kenyatta was immediately afforded the state security that would accompany a president-elect, traveling in a shiny black convoy from the tallying center to his election center. In a speech, he thanked Odinga — "my brother" — for a spirited campaign in an address to the nation, according to prepared remarks.

"My fellow Kenyans, today we celebrate the triumph of democracy, the triumph of peace, the triumph of nationhood," he said, adding later: "My pledge to you is that as your president I will work on behalf of all citizens regardless of political affiliation. I will honor the will of Kenyans and ensure that my government protects their rights and acts without fear or favor, in the interests of our nation."

If Kenyatta's victory holds, the son of Jomo Kenyatta will become the fourth president of Kenya since its independence from British colonial rule in 1963.