He formed the Maha Sinhala Party in the 1920s. In 1931 he was elected to the new State Council and after independence he assumed ministerial power. In 1952 he founded the Sri Lanka Freedom Party (SLFP), which was the leading partner in the coalition which won the 1956 elections, attracting left-wing and Buddhist support. As Prime Minister (1956–59) Bandaranaike pursued a policy of promoting the Sinhalese language, Buddhism, socialism, and neutrality. His policy alienated the Tamils. After his assassination in September 1959 by a dissident Buddhist monk, his widow, Mrs Sirimavo Bandaranaike, succeeded him as Prime Minister.