Kenyan voters, venting their frustration with a government that many said had failed to deliver on pledges to create jobs and curb corruption, have overwhelmingly rejected a proposed new constitution that would have given broad powers to President Mwai Kibaki.

With almost all ballots counted from Monday's vote, Samuel Kivuitu, chairman of the electoral commission, announced Tuesday that the proposed constitution had lost by 57 percent to 43 percent. The voting was peaceful despite a turbulent campaign and was widely seen as a test of the East African nation's democratic stability.

Kibaki, who had campaigned heavily for the revamped constitution, conceded defeat in a live television address to the nation.

"My government will respect the will of the people," said Kibaki, 74, looking somber and tired. "I would like to congratulate all of you for participating peacefully in this historic occasion."

Analysts expressed relief that voting day had been calm after weeks of ethnically charged campaigning. But they also said the defeat of the draft constitution could signal the crumbling of Kibaki's beleaguered government, which was popularly elected in 2002 but has recently lost support from key members of his own party.

"This is a real healthy moment for Kenya and Africa because it shows that democracy can flow here," said David Makali, an analyst with Kenya's Media Institute. "But what remains now is a real challenge and dilemma to the Kibaki administration. Can he make this work? He will have to show true leadership."

The referendum measure, which sought to overhaul the constitution for the first time since Kenya's independence from Britain in 1963, divided voters along ethnic lines and bitterly split Kibaki's ruling coalition.

A leading opponent was Raila Odinga, a charismatic cabinet minister whom Kibaki had once promised the prime ministership. On Tuesday, Odinga praised the referendum outcome as "historic days for our country."

The rejected constitutional changes would have given the president greater power to choose government officials and would have made the prime minister closer to a figurehead. Many voters favored an earlier draft of the charter that would have divided authority more evenly between the two posts, an important safeguard in a region where leaders often cling to power for decades.

The rivalry between Kibaki and Odinga has been exacerbated by tribal differences. Kibaki is from the dominant Kikuyu tribe and Odinga, currently minister of roads, is from another large tribe, the Luo. The referendum campaign was marred by tribal and personal slurs, with Kibaki accusing Odinga and other opponents of planning a coup and Odinga saying the constitution could win only through fraud.

In the weeks before the vote, nine people were killed in clashes with security forces during opposition rallies. There was widespread concern that polling would be rigged in favor of Kibaki, triggering further violence. But the voting was largely peaceful, although people appeared to generally cast their ballots along tribal lines.

On Tuesday, many Kenyans celebrated the results of the referendum, in which illiterate voters were able to participate by choosing between the symbols of a banana for the "yes" vote and an orange for the "no" vote.

"Maybe this is just the beginning for Kenya. Maybe things can really improve for us," said Beatrice Awori, 25, a mother of two who sells fruit at a street stall. "We sold many oranges today."

Analysts said Kibaki, whose election nearly three years ago was seen as a fresh start for Kenya after the autocratic rule of longtime President Daniel arap Moi, has proven a disappointing, lethargic leader and has allowed the country to drift back into the corrupt practices of the past.

They said that he would now have to give key cabinet positions to opposition figures, further weakening his presidency, and that he probably would not be able to win reelection in voting scheduled for 2007. Kibaki, once an energetic politician, suffered strokes and was in a near-fatal car crash in 2002.

"The shareholders of Kenya have spoken. We want leaders, not rulers," said Najib Balala, the culture minister and one of the senior officials who opposed the charter. He said Kibaki should "show good leadership and give opposition leaders more say in his government and give Odinga the prime minister slot."

Earlier this year, Kenya's leading anti-corruption official, John Githongo, resigned after uncovering several multimillion-dollar scams, including graft in official funding for HIV/AIDS programs and for improved passport security. Githongo, a popular figure, said his life had been threatened by associates of Kibaki's.

Kenyans in Nairobi cheer defeat of draft charter, which was voted down 57 percent to 43 percent in Monday's vote.