Former Meghalaya Chief Minister Mukul Sangma, along with 11 of the 17 Congress MLAs in the state joined the Trinamool Congress.
The Meghalaya MLAs submitted a letter to State Assembly speaker Metbah Lyngdoh at around 10 PM on Wednesday, informing him of their changes.
The development came a day after Congress leaders Kirti Azad and Ashok Tanwar as well as Pawan Varma, formerly of Janata Dal (United), joined the Trinamool Congress in Delhi in the presence of party chief Mamata Banerjee.
Hours earlier, Banerjee said her party would welcome political leaders from other parties who wished to join the Trinamool Congress's battle against the BJP.
Meghalaya is the latest state where the Trinamool Congress, in expansion mode over the last couple of months, has made an inroad. Its inroad has been at the cost of the Congress in Assam, Goa, Uttar Pradesh, Bihar and Haryana,.
Ms Banerjee, known to share a cordial relationship with Congress chief Sonia Gandhi, has not met her this time, although there was a buzz about a meeting.
Asked about the matter, the Trinamool Congress chief flared up. She had sought no appointment with Sonia Gandhi, as "they are busy with Punjab polls", Ms Banerjee said.
Then she pointedly added, "Why should we meet Sonia every time? It is not constitutionally mandated."
Meanwhile, the Trinamool Congress MLAs who joined the party overnight will address a press meet in Meghalaya's capital Shillong this afternoon.
The Trinamool Congress has been trying to expand its footprint in Tripura and Goa with an eye to the next round of assembly elections in these states. In Tripura, the party has been at loggerheads with the state's ruling BJP ahead of civic elections. In Goa, it is banking on Luizinho Faleiro, the state's former Chief Minister.
