In 1927, Sinha became member of the Legislative Council and in 1929 became General Secretary of the Bihar Pradesh Congress Committee (BPCC). In 1930, he played an important role in the Namak Satyagrah at Garhpura. He suffered severe scalding injuries to his hands and chest while being arrested, was imprisoned for six months and then was again arrested and imprisoned for two years during the civil disobedience movement. He was released after the Gandhi–Irwin Pact and again started with his nationalist work and work with the Kisan Sabha. On 9 January 1932 he was sentenced to two years of rigorous imprisonment and a fine of Rs. 1,000. He was released from Hazaribagh Jail in October 1933. He was involved in relief and rehabilitation after the 1934 Nepal–Bihar earthquake. He was the President of Munger Zila Parishad from 1934 to 1937. In 1935, he became member of the Bihar Legislative Assembly.