Sen became an MLA for the first time winning the
2008 Tripura Legislative Assembly election representing the Indian National Congress defeating Amitabha Datta of Communist Party of India (Marxist) by a margin of 2,410 votes. He retained the seat again on Congress ticket in the
2013 Tripura Legislative Assembly election beating Datta again by a margin of 1,844 votes. Later, he shifted to the Bharatiya Janata Party in 2017 and won the Dharmanagar seat in the
2018 Tripura Legislative Assembly election defeating Abhijit De, also of CPI (M) by a margin of 7,287 votes. He won a fourth consecutive term in the
2023 Assembly elections beating Chayan Bhattacharya of the Indian National Congress by a margin of 1,098 votes. == Death ==