In 1960, Moi founded the Kenya African Democratic Union (KADU) together with Ronald Ngala to challenge the Kenya African National Union (KANU) led by Jomo Kenyatta. KADU's stated aim was to defend the interests of the small minority tribes, such as the Kalenjin to which Moi belonged, against the dominance of the large Luo and Gĩkũyũ tribes that comprised the majority of KANU's membership.

KADU pressed for a federal system of constitution, while KANU was in favor of centralism. The advantage lay with the numerically stronger KANU, and the British government was finally forced to remove all provisions of a federal nature from the constitution. Later, KADU merged with KANU to form a giant national party – retaining the name KANU.