[10] Thakur was a votary of Hindi language, and as the education minister of Bihar, he removed English as the compulsory subject for the matriculation curriculum.

Malakar, who belongs to one of the Most Backward Classes (MBCs) of Bihar and had participated in the agitation supporting Karpoori Thakur’s reservation policy in the 1970s as a student activist belonging to the All India Students Federation (AISF) contends that the subaltern classes of Bihar – MBCs, dalits and upper OBCs had already gained confidence during the time of the Janata Party government.

[11] During the emergency in India (1975–77), he and other prominent leaders of Janata Party led the "Total Revolution" movement aimed at non-violent transformation of the Indian society.

[citation needed] In the 1977 Bihar Legislative Assembly election, the ruling Indian National Congress suffered a heavy defeat at the hands of Janata Party.

Janata Party was a recent amalgam of disparate groups including Indian National Congress (Organisation), Charan Singh's Bharatiya Lok Dal (BLD), Socialists and Hindu Nationalists of Jana Sangh.

The sole purpose of these groups joining together was to defeat Prime Minister Indira Gandhi, who had imposed a nationwide emergency and curtailed many freedoms.

[14] Infighting in the party broke over the question of Thakur's decision to implement the Mungeri Lal Commission report, that recommended the institution of reservations for Backward Castes in government jobs.

Upper caste members of the Janata Party tried to water down the reservation policy by unseating Thakur as Chief Minister.

[13][15] However, he could not last his full term because he lost the leadership battle in 1979 from Ram Sundar Das whom his adversaries placed against him and was replaced as chief minister.