The Trinamool Congress (TMC) is facing one of its most serious internal crises after allegations that signatures of several party legislators were forged on official documents submitted to the West Bengal Assembly. The controversy, dubbed "Signgate", has triggered a CID investigation, led to the expulsion of two TMC MLAs, and placed senior party leaders under scrutiny.TMC supremo Mamata Banerjee walks towards the residence of party MP Kalyan Banerjee, at Kalighat in Kolkata. (PTI)What is the forged signature scandal?The row centres on documents submitted to the West Bengal Assembly regarding the appointment of the Leader of the Opposition and the party's chief whip after the 2026 Assembly elections. Allegations emerged that signatures of several TMC legislators appearing on the documents were either forged or placed without their proper consent.The controversy gained momentum after complaints were reportedly raised by TMC MLAs Ritabrata Banerjee and Sandipan Saha, who questioned the authenticity of signatures used in a letter endorsing senior TMC leader Sovandeb Chattopadhyay for the post of Leader of the Opposition. Their complaints prompted a formal investigation by the West Bengal Crime Investigation Department (CID).The Assembly secretary subsequently lodged an FIR, and investigators began collecting statements and specimen signatures from legislators whose names appeared on the disputed documents. CID officials have already recorded statements from multiple TMC MLAs as part of the probe.Why has the scandal become a major embarrassment for TMC?The issue is particularly damaging because it has exposed signs of internal dissent within a party that has long been tightly controlled by its leadership. The scandal escalated further when TMC expelled MLAs Ritabrata Banerjee and Sandipan Saha, accusing them of anti-party activities. The expulsions came almost immediately after the legislators publicly questioned the signatures, fuelling speculation about growing fractures within the organisation.Senior TMC leader and national general secretary Abhishek Banerjee was also summoned by the CID in connection with the investigation, bringing the controversy closer to the party's top leadership.Coming close on the heels of a crushing poll defeat, the row has moved beyond a simple dispute over paperwork and has become a test of party discipline and leadership authority.Coming after a crushing election defeatThe forged-signature controversy has erupted barely weeks after TMC suffered a major defeat in the 2026 West Bengal Assembly elections, ending the party's 15-year rule in the state. The Bharatiya Janata Party secured a decisive victory, marking the first time it formed a government in West Bengal.The election result was a severe blow to TMC supremo Mamata Banerjee, whose party had dominated Bengal politics since 2011. Following the defeat, the party faced criticism over governance issues, corruption allegations, organisational weaknesses and post-election unrest.The signature-forgery allegations have intensified concerns about factionalism and dissatisfaction within TMC's ranks. Reports of absent legislators at party meetings and public disagreements among leaders have further added to the perception of a party struggling to maintain unity after losing power.What happens next?The CID investigation is continuing, with statements being collected from legislators and senior leaders. The probe will seek to determine whether any signatures were forged, who may have been responsible, and whether criminal wrongdoing occurred in the preparation of Assembly documents.For TMC, however, the political damage may already be significant. Coming so soon after the party's electoral defeat, the scandal has amplified questions about internal cohesion and leadership control, ensuring that the controversy remains one of the biggest challenges facing Mamata Banerjee's party as it attempts to rebuild in opposition.