Complex sentence: The original linchpins of the ODM were Uhuru Kenyatta's KANU party and Raila Odinga's LDP, but KANU have since pulled out, and the two groupings are headed by Raila Odinga (ODM) and Kalonzo Musyoka (ODM--Kenya).
Split into simpler sentences: The original linchpins of the ODM were Uhuru Kenyatta's KANU party and Raila Odinga's LDP. However, KANU has since pulled out, and the two groupings are headed by Raila Odinga (ODM) and Kalonzo Musyoka (ODM--Kenya).