Kolkata: Less than a month after the West Bengal Assembly elections, the Trinamool Congress appears headed for a formal split, with around 58 MLAs led by Ritabrata Banerjee submitting a letter to Assembly Speaker Rathindranath Bose.The development is likely to see control of the party's legislative wing slip from Chief Minister Mamata Banerjee's hands.Ritabrata Banerjee arrived at the Assembly on Wednesday morning carrying a letter signed by 58 rebel Trinamool MLAs. Following his arrival, the other legislators gathered at the Assembly and held a meeting.At the meeting, the MLAs unanimously elected Ritabrata Banerjee as the leader of the Trinamool Congress legislative party.Banerjee's name has also been proposed for the post of Leader of the Opposition.A letter bearing the signatures of the 58 rebel MLAs was subsequently submitted to Speaker Rathindranath Bose. Sources said the Speaker has accepted the letter.According to the sources, a separate letter submitted earlier by Abhishek Banerjee proposing Sobhondeb Chattopadhyay as the Leader of the Opposition was not accepted.In their submission to the Speaker, the rebel legislators also proposed the appointment of Shiuli Saha, Javed Khan and Sandipan Saha as deputy leaders, while Akhruzzaman, MLA from Raghunathganj, was named chief whip.Interestingly, the rebels have not claimed to be forming a new political party. Instead, they have reportedly continued to name Mamata Banerjee as their leader in the letter submitted to the Speaker.