As the General Secretary of the Awami League from 1966, Tajuddin coordinated the party during the tumultuous late 1960s and early 1970s, suffering imprisonment on several occasions. He formulated the early draft of the historic six-points demand that would eventually lead to the birth of Bangladesh. He coordinated the Awami League's election campaign for the 1970 Pakistani general election, in which the League gained a historic parliamentary majority. He also coordinated the non-cooperation movement of March 1971 precipitated by President Yahya Khan's delay in transferring power to the elected legislators. Tajuddin was among Sheikh Mujib's delegation in the Mujib-Yahya talks to settle the constitutional disputes between East and West Pakistan and transfer power to the elected National Assembly. Following the Pakistani army's crackdown on the Bangladeshi population on 25 March 1971, Tajudddin escaped to India. In the absence of Sheikh Mujib, he initiated the set up of the Provisional Government of Bangladesh in 1971 and headed it, operating in exile in India, as its prime minister.