TANA RIVER DELTA, Kenya — The first attacks began a year ago, pitting semi-nomadic Orma cattle herders against Pokomo maize farmers. The toll is now more than 180. One thing the warring Orma and Pokomo agree on is that politics is behind the extreme violence, as the country prepares for an election Monday. Kenyans are still recovering from a vote five years ago, when 1,100 people died as political violence executed along tribal lines tore across the country.