Shillong: In a big jolt to Congress in Meghalaya, 12 of its 18 MLAs, including former chief minister Mukul Sangma, joined the Trinamool Congress (TMC) yesterday. With this, the TMC has become the principal opposition party in the state. Mr Sangma, the Leader of Opposition in the state Assembly, was reportedly miffed with the Congress’ top leadership for allegedly being sidelined. He had also expressed resentment over the appointment of Lok Sabha MP Vincent H Pala as the president of the party’s state unit. Mamata Banerjee-led TMC is seeking to expand its footprints and enter national politics.