Actress-turned-politician Koel Mallick has officially resigned from the Rajya Sabha just months into her tenure.As per sources, Mallick met Vice President and Rajya Sabha Chairman CP Radhakrishnan and has submitted her resignation.This comes as another setback for Mamata Banerjee's Trinamool Congress (TMC).Yesterday, Mamata Banerjee's close aide Madan Mitra announced his resignation from all posts in the Mamata Banerjee-led TMC.The MLA from Kamarhati constituency joined the rebel faction led by Leader of Opposition Ritabrata.He said saying he was unable to work effectively within the party and alleged that the leadership was focused on promoting general secretary Abhishek Banerjee rather than strengthening the organisation. Mitra also claimed that his concerns had repeatedly gone unaddressed by the party leadership.Mamata Banerjee had recently nominated him as the chief whip of the MLAs.