Shillong, Nov 25 : In a major setback for Congress, at least 12 of the 18 party MLAs led by opposition leader Mukul Sangma have joined Trinamool Congress (TMC), party sources have said. Trinamool Congress's Rajya Sabha Member Sushmita Dev and a close associate of Sangma separately told IANS that the opposition leader along with 11 other Congress MLAs have joined the Trinamool Congress. Of the 12 Congress legislators who joined the Trinamool, eight MLAs are from Garo Hills, while four lawmakers are from Khasi Jaintia hills. With the latest political development, despite not winning any seat in 2018 Assembly elections to the 60-member assembly, the Trinamool Congress became the main opposition party in Meghalaya house. Former Meghalaya Chief Minister Sangma is said to be upset over the appointment of Shillong Lok Sabha Member Vincent H. Pala as the state Congress President in September. Sangma reportedly met Trinamool's National General Secretary Abhishek Banerjee in Kolkata last month triggering speculation amid a reported rift within the Congress in the northeastern state. Sangma had termed it as a courtesy meeting. /IANS