Basu was a member of the CPI(M) Politburo from the time of the party's founding (The CPI(M) was formed at the Seventh Congress of the Communist Party of India held in Calcutta from 31 October to 7 November 1964) in 1964 until 2008.
Basu merupakan anggota Politburo PKI(M) dari masa pendirian partai tersebut (PKI(M) dibentuk di Kongres Partai Komunis India Ketujuh yang diadakan di Kalkuta dari 31 Oktober sampai 7 November 1964) pada 1964 sampai 2008.