In yet another setback for former West Bengal Chief Minister and Trinamool Congress (TMC) supremo Mamata Banerjee, actor-turned-politician and Rajya Sabha MP Koel Mallick on Thursday resigned from the Upper House, becoming the fourth TMC member of Parliament to step down amid the party’s mounting political turmoil following its crushing defeat in the West Bengal Assembly elections.Mallick, also known as Rukmini Mallick, submitted her resignation to Rajya Sabha Chairman CP Radhakrishnan. “I do hereby resign from the membership of Rajya Sabha, which may please be accepted with immediate effect,” she wrote.Expressing gratitude to the House, she added, “I convey my sincere gratitude to the Deputy Chairman and all functionaries of the Rajya Sabha Secretariat for extending all help and cooperation during my tenure as a member of Rajya Sabha.”With her resignation, Mallick becomes the fourth TMC Rajya Sabha MP to quit after Sukhendu Shekhar Ray, Sushmita Dev and Prakash Baraik. Her exit has intensified speculation over growing dissent within the party.Adding to the political buzz, Mallick reportedly met Union Minister Bhupender Yadav at his official residence shortly after submitting her resignation, fuelling speculation about her future political plans and a possible shift in allegiance.Reacting sharply to the developments, Mamata Banerjee asked party leaders contemplating an exit to leave before the party’s July 21 Shaheed Diwas rally.”She has gone to meet a BJP leader and resigned. I want to inform everyone that she had earlier emailed her resignation. Those who want to leave under the pressure of the BJP, police, court cases, ED, CBI or CID investigations, I request them to do so before July 21,” Banerjee said in a video message.Mallick, along with Supreme Court lawyer Menaka Guruswamy and former IPS officer Rajeev Kumar, was elected to the Upper House by the TMC in March this year.The latest resignation comes amid a broader political churn in West Bengal. Earlier, as many as 20 TMC Lok Sabha MPs resigned from the party and later merged with the Nationalist Citizens Party of India while extending support to the BJP-led National Democratic Alliance (NDA). Notably, a day earlier, another close aide of Mamata Banerjee, Madan Mitra joined the rebel faction led by Ritabrata Banerjee.The successive resignations from both the Lok Sabha and the Rajya Sabha have dealt a significant blow to the TMC, raising questions over the party’s internal cohesion and political strategy in the aftermath of its electoral setback.