West Bengal has become saffron. Mamata BanerjeeThe 15-year rule of BJP ended and the Bharatiya Janata Party (BJP)BJP) is all set to form his first government in the state.So, what has contributed to this decisive political shift in the electoral landscape of the state? Well, there were many factors that contributed to the result, but the one that was most controversial was the Revision of Voter List – SIR.

How did SIR become a decisive issue of elections?

The Special Intensive Revision of Electoral Rolls (SIR) emerged as a central and intensely competitive factor shaping the 2026 West Bengal electoral contest. This practice led to the deletion of approximately 91 lakh names – approximately 12% of the electorate – leading to a significant change in the voter base ahead of polling. Of these, more than 60 lakh were classified as deceased, while the status of 27 lakh was pending or under investigation.According to various reports, a large proportion of the affected people were Muslims, while some sections of the Matua community and many Hindus were also affected. The BJP framed the SIR as a necessary cleanup of the voter list aimed at removing ‘invalid’ or duplicate entries. But Mamata’s party countered this and termed the exercise as systematic disenfranchisement, leading to an open war of words.Despite these competing narratives, the scale and spread of deletions changed voting trends in a way that coincided with the BJP’s gains across the state. The total voter base declined from 7.66 crore to about 7.04 crore, excluding those still subject to decision.

Electoral data: mapping SIR deletions to results

A closer look at the constituency-level results reveals a strong correlation between SIR-linked deletions and BJP gains.The BJP has improved its performance in seats where names have been removed on a large scale, whether the number of names removed is above 25,000 or below that limit. In the 169 assembly constituencies where over 25,000 names were removed, TMC dominated in 2021 and won 128 seats compared to BJP’s 41. However, this time the balance changed to a great extent.On the remaining 124 seats, where deletions were less than 25,000, the BJP’s tally increased dramatically from 36 to 108 in 2021 – representing a three-fold increase. This indicates that the party’s gains were not limited to the areas with the highest deletions, but extended to the broader electoral spectrum affected by the amendment practice.

Of the 38 constituencies where ‘logical anomaly’ deletions were highest, TMC won 34 seats in 2021. In the current election, its tally dropped to 22, underscoring the erosion of its earlier dominance in these areas.However, even in high deletion regions, the results were not uniform. Of the six constituencies with the highest SIR deletions, TMC managed to retain only four – Chowringhee, Shamsherganj, Metiyaburuz and Kolkata Port – while the BJP captured Jorasanko and Howrah North. It is noteworthy that in the last elections, all the six seats were won by the Mamata led party.Apart from Jorasanko, the BJP made significant gains in Kolkata and border areas, winning in Maniktala, Shyampukur and Cossipore-Belgachia in Kolkata North, and extending its lead 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 where more than 25,000 deletions were recorded and which were previously held by Trinamool.Farakka was one of the exceptions. Despite seeing over 25,000 deletions, the BJP failed to win the seat. Congress candidate Motab Shaikh, whose name was initially removed during the SIR, successfully appealed through the Appellate Tribunal – one of the 19 set up following Supreme Court directions – and secured restoration of his voting rights. He won the seat by defeating BJP candidate Sunil Chaudhary by a margin of 8,193 votes.

Margins, deletions and electoral effects

The relationship between extinction and margin of victory further underlines the impact of SIR. Of the 187 seats from which more than 5,000 names were removed, the BJP won 119 seats. In these constituencies, the number of excluded voters was more than the margin of victory in 47 seats.BJP’s deletion of 28 seats out of 119 seats recorded more than the victory margin of its candidates. Of these, 26 seats were won by Trinamool in 2021.Of the 20 constituencies with the highest number of deletions after the decision, TMC won 13, BJP six and Congress one. However, in the 2021 elections, all 20 seats were secured by Trinamool, highlighting its relative disadvantage this time.

BJP’s ‘Security Fort’ to ensure smooth SIR process

The SIR exercise was also accompanied by unprecedented security deployment. More than 2.4 lakh personnel of the Central Armed Police Forces were deployed across West Bengal – more than three times the level seen in 2021 – in what the BJP described as a ‘security fortress’.Widespread deployment, along with close monitoring by the Election Commission of India, became another important pillar in enabling what the BJP described as “free and fair voting” in the politically unstable state.At one point, Mamata approached the Supreme Court over using only central government employees as counting observers, but the court refused to intervene.

The Mutua Factor: Identification, Concern, and Consolidation

The Matua community emerged as another important electoral variable shaped by the SIR practice. Despite discontent over mass deletions and concerns over citizenship documents under the CAA, the BJP retained its hold in Matua-dominated areas like Bongaon and Nadia.The deletion of nearly 1.2 lakh names under SIR created social and political tension in these areas. In six assembly constituencies of Nadia, more than 90% of the people placed under the decision did not find a place in the final voter list. A similar pattern was seen in Bongaon, where extinction rates ranged from 67% to 88%.Bagdah became the focal point of the competition, which saw a high-profile battle within the influential Thakurbari family. BJP candidate Soma Thakur defeated Trinamool MLA Madhuparna Thakur by 34,321 votes. The BJP also retained Bongaon North and secured Haringhata by a substantial margin.Despite concerns over the boycott, Matua voters – a marginalized Hindu sect consisting mainly of the Namasudra Scheduled Caste group – appeared to be uniting behind the BJP.

Disenfranchisement vs. electoral integrity

Clearly, the SIR exercise was the dominant narrative throughout the election and will continue to be debated in the times to come. The opposition sees SIR as a tool to target and purge its voters, while the BJP justifies it as a much-needed exercise to clean up the voter rolls.