Nairobi, Kenya (CNN) -- President Mwai Kibaki proclaimed Thursday a "happy end" as an overwhelming majority of Kenyans voted to adopt a new constitution that is sure to bring big change to the East African country.
"The historic journey that we began over 20 years ago is now coming to a happy end," Kibaki said while addressing the nation.
But he tempered national euphoria by reminding Kenyans that implementing a new constitution will be a difficult task.
"The journey ahead of national renewal will not be easy," he said. "There will be challenges along the way. But it is important that we look forward with renewed optimism to better days ahead."
U.S. President Barack Obama called the vote a "step forward" for Kenya and its people, in a statement released by the White House Thursday. He said the electoral process was "credible" and "transparent," and that the results show Kenyans' desire for a stable and prosperous future.
Obama's father grew up in a village in western Kenya.
He also applauded the fact that the election came and went without the kind of violence that marred the 2007 presidential vote. Obama called the process a "testament" to Kenya's people.
The country's new constitution would remove power from the presidency and create a more decentralized political system. The constitution would also bring in a bill of rights, allow dual citizenship for Kenyans -- sure to be popular with Kenya's large and loyal diaspora community -- and allow for land reform.
Results by the Interim Independent Electoral Commission showed "Yes" won the referendum with 67.2 percent while "No" had 30.3 percent.
"I do declare that the proposed constitution is hereby ratified," said Ahmed Isaack Hassan, chairman of the electoral commission.
Leading opponents of Kenya's proposed constitution conceded defeat earlier Thursday. Higher Education Minister William Ruto, a leader of the "No" team, said despite his camp's loss, every Kenyan " is a winner" in the outcome.
"It is necessary to create a win-win for the country," Ruto said flanked by senior members of the "No" camp.
Despite the win by the "Yes" team, Ruto said, the government should address the complaints of those who rejected the referendum.
"It is not only necessary, it is mandatory," he said.
Many Kenyans were already celebrating before they heard the official results.
The Daily Standard newspaper couldn't wait for the announcement. "Yes it is!" rang the headline in the morning paper.
"Now it's time to reunite the country behind the outcome," the newspaper said in an editorial.
Kenyans voted against the constitution by a significant majority in the restive Rift Valley, where "No" politicians and Christian church leaders focused their campaigning. Churches feared the new constitution would offer abortion on demand and give Muslims special rights.
"The results do not nullify our concerns," said a church statement Thursday.
Others applauded the peaceful vote. After the last presidential election three years ago, political violence claimed several hundred lives and displaced hundreds of thousands of people.
"We very much welcome reports which indicate that Kenyans were able to vote in a free, fair and peaceful atmosphere," said a statement from the Panel of Eminent African Personalities. "The high voter turnout nationally reflects the strong desire of Kenya's people to help shape their country's future."