Senior Trinamool Congress leader and Rajya Sabha MP Mukul Roy announced his resignation from the party on Monday after months of being sidelined by chief minister Mamata Banerjee.Roy, the partys former all India general secretary who was considered the number 2 in the party after Banerjee, said he resigned from the Trinamool Congress working committee and would quit the Upper House and party primary membership after Durga Puja, which ends on September 30.It is with a heavy heart and pain that I announce this. This was a party that I helped set up on December 17, 1997,said the 63 year old MP in Kolkata.Roy was removed from the position of party general secretary in 2015 after his name came under the CBI scanner in the multi crore Saradha chit fund case. He was further sidelined after reports of his hobnobbing with BJP leaders reached Mamata Banerjee.I have sent an email this morning informing my decision to step down from the working committee. I shall resign from Rajya Sabha immediately after the pujas. About eight months are left for my tenure to end in the Upper House, Roy said at a press conference on Monday in Kolkata.At that time I shall also step down from the primary membership of the party.Roys announcement caps months of growing rift with chief minister Mamata Banerjee,who was seen sidelining her former trusted general in the party.This is the time of the pujas and none will be interested in petty politics.So I shall explain why I took the decision in detail later, he said. Roy said that he will spend the next few days celebrating Durga puja.