Agartala, March 24 : Ruling BJP MLA Biswa Bandhu Sen was elected the Speaker of the Tripura assembly on Friday defeating opposition CPI-M-Congress joint candidate Gopal Chandra Roy. Septuagenarian Congress-turned-BJP leader, Sen secured 32 votes, while Roy, one of the three Congress MLAs, bagged 14 votes. The tribal-based Tipra Motha Party (TMP), which has 13 members in the assembly, walked out from the house just before the starting of the Speaker's election expressing their displeasure over the sitting arrangements in the house. The TMP supremo Pradyot Bikram Manikya Deb Barman earlier promised to support the CPI-M-Congress joint candidate and the party's legislature party leader Animesh Debbarma, who is also the incumbent leader of the opposition, was one of the proposers in Roy's nomination paper. Union Home Minister Amit Shah on Thursday informed Deb Barman that the Centre would appoint an interlocutor by March 27 to study the "constitutional solutions" to TMP's demands for more autonomy and socio-economic development of the tribals, who constitute one third of Tripura's four million populations. Political circles said that after Shah's phone call, and subsequently, Deb Barman's meeting with Assam Chief Minister Himanta Biswa Sarma, the TMP supremo changed his stand on the Speaker's elections. Sen, a four-time MLA from Dharmanagar in North Tripura district since 2008, was the Deputy Speaker in the previous assembly. In the February 16 elections to the 60-member Tripura assembly, the BJP secured 32 seats while its ally Indigenous People's Front of Tripura (IPFT) got one seat while the opposition CPI-M managed 11 seats and the Congress bagged three seats. Later, Union Minister of State Pratima Bhowmik, who was elected to the Tripura assembly in the last month's elections from the Dhanpur assembly constituency, resigned from the house. /IANS