Washington - Former US president Barack Obama called Monday on Kenyans to hold a peaceful and untainted election, speaking out on the eve of a crucial vote in the East African country where his father was born."I urge Kenyan leaders to reject violence and incitement; respect the will of the people," Obama said in a statement.Tuesday's elections pit President Uhuru Kenyatta against his historic rival Raila Odinga, who has run for president thrice and lost each time.The polls are seen as a test of Kenya's progress since a disputed 2007 election sparked two months of violence which left more than 1 100 dead and 600 000 displaced.Elections in 2013 were largely peaceful, although Odinga accused Kenyatta's Jubilee Party of poll fraud after massive glitches with the electronic voting system."I urge all Kenyans to work for an election - and aftermath - that is peaceful and credible, reinforcing confidence in your new Constitution and the future of your country," said Obama, who left office in January after serving two four-year terms.Besides deciding the presidential race, Kenyans will cast ballots in six different elections, choosing governors, lawmakers, senators, county officials and women's representatives in local races also rife with tension.Obama said Kenyans certainly recall "the needless pain and agony" of the 2007 election aftermath and warned against resorting to violence again."In Kenya's election we have already seen too much incitement and appeals based on fear from all sides. But I also know that the Kenyan people as a whole will be the losers if there is a descent into violence," Obama said.