Assembly Speaker Ramendra Chandra Debnath told reporters that he had received a letter from Congress legislator Sudip Roy Barman, who he said was accompanied by three legislators.
“The letter was signed by six Congress MLAs informing me that they have joined the Trinamool Congress,” Mr Debnath said.
“I would call all the six Congress MLAs for individual hearing and verification of their signature. After consulting the rules and experts, I will take a final decision in this regard in a day or two,” he said.
Trinamool Congress Vice President Mukul Roy came here on Tuesday, his second visit to the Left-ruled state in five days.
Besides Roy Barman, the other Congress MLAs who signed the letter include Ashish Saha, Biswabandhu Sen, Diba Chandra Hrangkhawl, Pranjit Singha Roy and Dilip Sarkar.
Pranjit Singha Roy, who is out of Tripura, and the ailing Dilip Sarkar were not present when Roy Barman handed over the letter to the speaker.
Sudip Roy Barman recently resigned from the post of Congress Legislator Party leader protesting against the Congress-Left electoral alliance in West Bengal.
Mr Barman was the opposition leader in the Tripura assembly.
The Congress now has only three legislators in the 60-member house.
On Monday, another Congress legislator, Jitendra Sarkar, resigned from the Tripura assembly and said he would rejoin the ruling Communist Party of India-Marxist (CPI-M).