After Poland regained her independence in 1918, he remained an active politician. In 1920 he co-founded the National Workers' Party (NPR), which he headed until 1923 and of which he remained a deputy chairman until 1933. As the most prominent politician of the NPR, between 1921 and the May coup d'état of 1926 he was the minister of labour and social policies in the government of Poland. In 1928 he was elected a member of the Sejm, a seat he held until 1935. In 1937 he moved to the Labor Party and became one of its leaders.