As leader of the Abako (Association des Bakongo) movement of his own lower Congo river Bakongo people, Kasa Vubu was elected president by the Congo's new national assembly, taking office on the country's independence from Belgium (June 30, 1960).
The new republic was immediately disrupted by political and military strife and regional secessionist movements, while the central government was paralyzed by conflict between the conservative Kasa Vubu and his radical prime minister Patrice Lumumba.
On September 5 Kasa Vubu and Lumumba each announced the other's dismissal, creating a stalemate that was only ended on September 14 with army commander Joseph Mobutu's seizure of power in support of Kasav Vubu. Lumumba was later handed to secessionist forces in the southern province of Katanga and killed.
Over the next five years, Kasa Vubu presided over a succession of weak governments, in July 1964 appointing former Katangan secessionist leader Moise Tshombe prime minister to use European mercenaries against leftist rebels. Mobutu seized power a second time on November 25, 1965, this time deposing Kasa Vubu and subsequently declaring himself head of state.