In 1958 Sendwe attended the Brussels Expo, working as a medical assistant at the African Personnel Reception Center. Afterwards he joined the short-lived Mouvement pour le Progres National Congolais, a party formed by attendees of the exposition. On 5 February 1959 Sendwe brought BALUBAKAT into Tshombe's Confédération des associations tribales du Katanga (CONAKAT) party on the condition that it be able to maintain a significant amount of autonomy. He initially shared the xenophobic stances of CONAKAT, but soon grew concerned that its hostility toward immigrants would extend to incoming Baluba. Sendwe was also worried by Tshombe's close connections to the Belgians and was repulsed by the prominence of several of his political rivals within the party's ranks. BALUBAKAT began to form two trends, one sympathetic to CONAKAT, and the other supportive of the Mouvement National Congolais (MNC). The latter was led by Sendwe. In October he sent a letter to Baudouin, King of the Belgians, urging him to oppose efforts at "dismantling the immense country" created by his predecessors.