Kenyan opposition supporters clashed with police and threw up burning barricades on Thursday to challenge the legitimacy of an election rerun likely to return Uhuru Kenyatta as president of East Africa’s chief economic and political powerhouse. In the western city of Kisumu, stone-throwing youths heeding opposition leader Raila Odinga’s call for a voter boycott were met by live rounds, tear gas and water cannon. There were no immediate reports of casualties and Reuters found no polling stations open. In Kibera and Mathare, two volatile Nairobi slums, riot police patrolled. Protesters set fires in Kibera early in the morning. Nearly 50 people have been killed by security forces since the original August vote that Kenyatta won but which was annulled by the Supreme Court due to procedural irregularities.