West Bengal has turned saffron. Mamata Banerjee’s 15-year rule has ended and Bharatiya Janata Party (BJP) is all set to form its first government in the state. So, what contributed to this decisive political shift in the state’s electoral landscape? Well, there were multiple factors that contributed to the outcome, but the one that was most contentious was the revision of the electoral rolls – SIR.
How SIR became the defining issue of the elections
The Special Intensive Revision (SIR) of electoral rolls emerged as a central and deeply contested factor shaping the 2026 West Bengal electoral contest. The exercise led to the removal of close to 91 lakh names — roughly 12% of the electorate — significantly altering the voter base ahead of polling. Of these, over 60 lakh were classified as deceased, while the status of 27 lakh remained pending or under scrutiny.According to various reports, a large proportion of those affected were Muslims, while sections of the Matua community and many Hindus were also impacted. BJP framed the SIR as a necessary clean-up of electoral rolls aimed at removing ‘illegal’ or duplicate entries. But Mamata’s party countered this and described the exercise as systematic disenfranchisement leading to open war of words.Regardless of these competing narratives, the scale and spread of deletions reshaped voting trends in a manner that coincided with BJP’s surge across the state. The total voter base dropped from over 7.66 crore to around 7.04 crore, excluding those still under adjudication.
How SIR impacted the 2026 state elections in Bengal
Electoral data: Mapping SIR deletions to outcomes
A closer look at constituency-level outcomes suggests a strong correlation between SIR-linked deletions and BJP’s gains.BJP improved its performance across seats that witnessed sizeable deletions, irrespective of whether the number of names removed exceeded 25,000 or fell below that threshold. In 169 assembly constituencies where more than 25,000 names were deleted, TMC had dominated in 2021, winning 128 seats compared to BJP’s 41. This time, however, the balance shifted significantly.In the remaining 124 seats, where deletions were lower than 25,000, BJP’s tally rose dramatically from 36 in 2021 to 108 — marking a three-fold increase. This indicates that party’s gains were not limited to areas with the highest deletions but extended across a broader electoral spectrum influenced by the revision exercise.Among the 38 constituencies where ‘logical discrepancy’ deletions were the highest, TMC had won 34 seats in 2021. In the current election, its tally dropped to 22, underlining the erosion of its earlier dominance in these pockets.Even in high-deletion zones, however, outcomes were not uniform. Among the six constituencies with the highest SIR deletions, TMC managed to retain only four — Chowringhee, Shamsherganj, Metiaburuz and Kolkata Port — while BJP captured Jorasanko and Howrah North. Notably, all six seats had been won by the Mamata-led party in the previous election.Apart from Jorasanko, BJP made significant inroads in Kolkata and bordering areas, securing victories in Maniktala, Shyampukur and Cossipore-Belgachhia in Kolkata North, and extended its gains to Rashbehari, Behala East, Bidhannagar, Baranagar, Dum Dum, Dum Dum North and Rajarhat-Gopalpur. It also won seats in Behala West, Tollygunge and Jadavpur — all constituencies that had recorded over 25,000 deletions and were previously held by Trinamool.Farakka was one of the exceptions. Despite witnessing over 25,000 deletions, BJP failed to win the seat. Congress candidate Motab Shaikh, whose name had initially been removed during the SIR, successfully appealed through an appellate tribunal — one of 19 set up following Supreme Court directions — and secured restoration of his voting rights. He went on to win the seat by beating BJP candidate Sunil Chowdhuri with a margin of 8,193 votes.
Margins, deletions and electoral impact
The relationship between deletions and victory margins further underscores SIR’s impact. Of the 187 seats that saw over 5,000 names deleted, BJP won 119. In these constituencies, the number of excluded voters exceeded the margin of victory in 47 seats.Within BJP’s tally of 119 seats, 28 recorded deletions higher than the victory margin of its candidates. Of these, 26 had been won by Trinamool in 2021.Among the 20 constituencies with the highest number of deletions after adjudication, TMC won 13, BJP six and the Congress one. However, in the 2021 elections, all 20 had been secured by the Trinamool, highlighting the relative disadvantage it faced this time.
BJP’s ‘security fortress’ to ensure smooth SIR process
The SIR exercise was accompanied by an unprecedented security deployment. Over 2.4 lakh personnel from Central Armed Police Forces were stationed across West Bengal — more than three times the levels seen in 2021 — creating what the BJP described as a ‘security fortress’.The extensive deployment, coupled with tighter oversight by the Election Commission of India, became another key pillar in enabling what the BJP described as “free and fair voting” in a politically volatile state.At one stage, Mamata approached the Supreme Court over the use of only central government employees as vote-counting supervisors, but the court declined to intervene.
The Matua factor: Identity, anxiety and consolidation
The Matua community emerged as another critical electoral variable shaped by the SIR exercise. Despite discontent over large-scale deletions and anxieties surrounding citizenship documentation under the CAA, BJP retained its foothold in Matua-dominated regions such as Bongaon and Nadia.The removal of approximately 1.2 lakh names under SIR triggered social and political tensions in these areas. In Nadia’s six assembly constituencies, over 90% of those placed under adjudication did not make it to the final electoral rolls. A similar pattern was observed in Bongaon, where deletion rates ranged from 67% to 88%.Bagdah became a focal point of this contest, witnessing a high-profile battle within the influential Thakurbari family. BJP candidate Soma Thakur defeated Trinamool MLA Madhuparna Thakur by 34,321 votes. BJP also retained Bongaon Uttar and secured Haringhata with substantial margins.Despite concerns over exclusion, the Matua electorate — a marginalised Hindu sect primarily comprising the Namasudra scheduled caste group — appeared to consolidate behind BJP.
Disenfranchisement vs electoral integrity
Clearly, the SIR exercise was the most dominant narrative throughout the elections and will continue to be debated for times to come. The opposition sees SIR as a tool to target and purge its voters, while BJP justifies it as a much-needed exercise to cleanse electoral rolls.