A Kenyan man, wearing a box with pictures of U.S. President Barack Obama and Kenya’s Prime Minister Raila Odinga, cheers at a rally to launch campaigns for the Constitution Referendum in the capital Nairobi, May 15, 2010. As Kenyans prepare to vote in a referendum on constitutional reform in August, many remain haunted by the tribal bloodletting that convulsed east Africa’s largest economy in early 2008.