Uhuru Kenyatta, Kenya's deputy prime minister, has won Kenya's presidential election with a slim margin of 50.03 percent of votes cast, according to provisional figures announced by the election commission.
Kenyatta, 51, who faces international charges of crimes against humanity, secured 6,173,433 votes out of a total of 12,338,667 ballots cast, the commission announced on Saturday, indicating that he had secured the more than 50 percent of votes needed for a first round win.
The national election commission said it expected to announce the final result at 11am (08:00 GMT) on Saturday.
Senior advisors to Prime Minister Raila Odinga, who was placed second, have said he will take his case to court if Kenyatta is declared the winner.
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Both Kenyatta and Odinga have raised questions about the vote process and irregularities.
Turnout was estimated by election officials at more than 70 percent of the 14.3 million eligible voters, who were undeterred by pockets of violence that killed at least 15 people.
Kenyatta has led since results started trickling in after polls closed on Monday.
He is due to go on trial at the International Criminal Court (ICC) in The Hague on charges of crimes against humanity linked to the violent aftermath of the country's 2007 election,
Al Jazeera’s Mohammed Adow, reporting from Nairobi, said Kenyatta’s supporters in the capital and his voting strongholds of central Kenya and the Rift Valley were celebrating the narrow victory because an outright win in the first round was a “do or die” situation for the deputy prime minister.
“He wanted to get the minimum needed for him to get an outright win, because he knew if it went to a run-off, the possibility of Raila Odinga bouncing back and beating him in the second round was very high,” Adow said.
Despite the delays and technical glitches, international observers have broadly said the vote and count were transparent.
"What has been really impressive thing in this election has been the robustness of public confidence not just in the election commission but also in the credibility and ability of the courts to resolve these problems," Al Jazeera's Peter Greste reported from Nairobi.
The tallying process has been marred by allegations from both sides, including charges by Odinga's party that results had been "doctored".
The political coalition led by Odinga called for a stop to a tallying process it said "lacked integrity".
The statement by Odinga's running mate, Kalonzo Musyoka, said the counting process should be restarted using primary documents from polling stations, but the election commission insisted there was no way to doctor the results.
Kenyatta's party had also raised concerns over the slow-moving vote count, complaining that the inclusion of spoiled ballots in the overall total could potentially tip the balance in favour of a second round.
However, the European Union ambassador to Kenya, Lodewijk Briet, said the vote counting was sound and should be allowed to continue.
Educated in the US at Amherst College, where he studied political science and economics, Kenyatta is considered the top political leader of the Kikuyu people, Kenya's largest tribe making up some 17 percent of the population.
However, he also appeals to large numbers of Kenyans from different ethnic backgrounds, able to mingle not only with the elite he was born into but also with the average Kenyan, cracking jokes using local street slang.
While a leaked 2009 US diplomatic cable described him as "bright and charming, even charismatic", it also noted that he "drinks too much and is not a hard worker".
In the early 1990s, Kenyatta joined with the sons of other independence heroes to call for reform but gradually drew closer to former President Daniel arap Moi.
Kenyatta threw his weight behind then incumbent President Mwai Kibaki in the December 2007 election, a poll that rapidly descended into chaos and left over 1,100 dead and forced hundreds of thousands from their homes.
Delays in the 2007 vote count saw violence erupt over suspicion that Kibaki was stealing the election from Odinga, and killings mainly targeting Kikuyus spread across the country.
The Kenya National Commission on Human Rights has accused Kenyatta of attending meetings in early 2008 to plan for retaliatory violence by the Kikuyu.
Adow said concerns of a repeat of the 2007 violence remained, but the difference now was the Kenyan judiciary which Odinga had said he had no faith in had been reformed.
“It is now fully reformed and Raila Odinga has already said he will take his contest, all the election results to court,” Adow said.
“That is what is instilling more confidence in Kenyans.”
ICC prosecutors say he mobilised the Mungiki - a sect-like Kikuyu criminal organisation known for skinning and beheading its victims - to attack opposition supporters.
Kenyatta, listed by Forbes magazine as one of the richest people in Africa, faces five counts including orchestrating murder, rape, forcible transfer and persecution in the polls' aftermath.
Kenyatta has repeatedly said he will co-operate with the ICC, even though it could mean he will be absent from Kenya for long periods, with the trial expected by many to stretch for several years.