Kenya's deputy prime minister Uhuru Kenyatta, who faces an international crimes against humanity trial, took an initial lead in presidential elections Tuesday, the first since disputed polls five years ago sparked a wave of violence.
Kenyatta edged ahead in partial results over rival Prime Minister Raila Odinga, who says he was robbed of victory in 2007 when disputed results triggered bloody ethnic violence in which more than 1,100 people were killed and 600,000 were forced to flee their homes.
While millions of Kenyans turned out peacefully on Monday for the elections, how they react to the final results will be key to stability in the regional powerhouse.
Voters stood for hours in long snaking lines several people thick outside polling stations to take part in one of the most complex elections Kenya has ever held.
Some 40 percent of the almost 32,000 polling stations had sent partial results 24 hours after official centres closed to the national tallying centre in Nairobi, with so far five million valid votes counted from the 14.3 million registered voters.
Of those counted at 5:15 pm (1415 GMT), Kenyatta had won almost 2.7 million or 53 percent of valid votes cast against Odinga with 2.12 million or 41 percent, a gap that could still be easily overturned.
But a staggering 320,000 ballots were rejected, making up more than five percent of votes cast and totalling more than the third candidate in the race, deputy prime minister Musalia Mudavadi, who has less than three percent of votes so far.
None of the other five candidates had taken more than one percent.
"This election is a turning point, and its outcome will determine whether the country will proceed as a civilised state," the Daily Nation newspaper said, adding that all Kenyans must "be ready to accept the election results."
Hours before polling stations opened, at least six policemen and six attackers -- said to be a separatist group -- were killed in clashes in the Indian Ocean coast, while one person was wounded after several bombs exploded in Mandera, on the northeastern border with war-torn Somalia.
But while few other incidents during polling were reported, there were complaints at the widespread failure of electronic biometric voting registration (BVR) kits introduced by the Independent Electoral and Boundaries Commission (IEBC) to frustrate potential rigging.
The BVR failure meant stations used paper records and manual registration.
-- Questions at slow pace of tally --
Kalonzo Musyoka, Kenyan vice-president and Odinga's running mate, told reporters they were worried at the "failure of the IEBC electronic registers as well as the huge numbers of spoilt votes", but urged supporters to remain calm.
IEBC chairman Ahmed Issack Hassan said the body was investigating complaints of voting irregularities from political parties, and said the large number of spoilt ballots were a "concern".
"I want to assure the candidates and political parties, please don't jump to conclusions: your job is to contest the election, our job is to organise them," Hassan said, adding that he did not expect full preliminary presidential results until at least Wednesday.
In the western town of Kisumu -- heartland of Odinga and scene of bitter clashes in 2007 when his supporters grew angry at what they saw as rigged results -- grim-faced residents watched the partial results being broadcast on television.
"There is a lot of tension, people are not happy with how things are going," said Nicholas Ochieng, 24.
To win, a candidate must take more than 50 percent of votes -- as well as winning at least 25 percent of votes in more than half of all counties -- to avoid a second round runoff, due within a month after final results.
The results of the 2007 poll which President Mwai Kibaki won against Odinga sparked a wave of protests, notably because of the lack of transparency in the way the tallying was done.
Odinga and his rival Kenyatta -- the son of independent Kenya's founding president as well as one of Africa's richest and most powerful men -- have publicly vowed there will be no repeat of the 2007-08 bloodshed.
But crimes against humanity trials later this year at The Hague-based International Criminal Court (ICC) for Kenyatta and running mate William Ruto have raised the stakes: should they win the vote, the president and vice-president could be absent for years.
Kenyatta faces five counts including orchestrating murder, rape, forcible transfer and persecution.
The 2007-2008 violence exposed deep tribal divisions and widespread disenchantment with the political class and shattered Kenya's image as a beacon of regional stability.
However, a new constitution devolving powers has made the poll less of a winner-takes-all race.
Kenyans cast six ballots on Monday, voting for a new president, parliamentarians, governors, senators, councillors and special women's representatives.