So, did 'SIR ji' help BJP in Bengal? Data suggests it did

“If 10 per cent of the electorate does not vote and the winning margin is more than 10 per cent…what will happen? Suppose margin is 2 per cent and 15 per cent of the electorate who are mapped could not vote, then maybe… we are not expressing any opinion, but we would definitely have to apply our minds,” observed Justice Joymalya Bagchi in the Supreme Court during hearing of petitions challenging SIR.

Justice Bagchi's half-articulated apprehension appears to be borne out by the results of the West Bengal Assembly elections declared on Monday, 4 May.

'In 105 seats that the Bharatiya Janata Party won in West Bengal, the total number of voters deleted during the special intensive revision exceeds its margin of victory,' reported a data analysis by Scroll.

In a separate analysis The Wire reported, 'In 150 seats, more than half of West Bengal’s 294, total deletions were greater than victory margins, and BJP won 99. In 2021, it had won just 19 of these.' 

The bulk of these 105 seats have never been won before by the BJP. Banerjee’s party ended up losing 129 seats it had held to the BJP. The Hindutva party, on the other hand, won every single seat that it had won five years ago.

The analysis by both the portals underscores that of the 105 seats, 86 were never won by the BJP. Bengal has 294 Assembly seats in all, and the BJP secured a two-thirds majority to end outgoing chief minister Mamata Banerjee’s 15-year reign in the state. Both the news portals cited several results to indicate how SIR may have affected the final outcome.

1. The Indus seat in Bankura was won by the BJP this time by just 900 votes. SIR had deleted 7,515 voters in the constituency.

2. BJP won the Jadavpur Assembly seat in south Kolkata by a margin of 27,716 votes. The SIR excluded more than 56,000 names in the constituency, a stronghold of the CPI(M), which polled a little over 41,000 votes.

3. Aroop Biswas, a minister in the outgoing government, lost the Tollygunge seat by 6,013 votes. The total number of voters deleted by SIR was 37,889.

4. Mamata Banerjee also lost her Bhabanipur seat to BJP heavyweight Suvendu Adhikari by 15,105 votes, while the SIR had deleted over 51,000 voters.

5. In Satgachhia, the BJP’s victory margin was 401 votes while there were 17,669 ASDD deletions and 8,785 'under adjudication' voters were found ineligible

6. In Rajarhat New Town, the BJP’s victory margin of 316 votes followed over 63,000 total deletions.

7. In Raina, BJP won by 834 votes, while total deletions crossed 23,000.

8. In Jangipur, BJP won by 10,542, while deletions stood at 36,581 in a constituency with over 51 per cent Muslim population.

In West Bengal, SIR was a contentious exercise which dragged on for six months until days before polling and culminated in a total of about 91 lakh names being deleted, shrinking the state’s voter rolls by nearly 12 per cent. Of the 91 lakh total deletions, at least 34 lakh voters are known to have filed petitions against their deletion before appellate tribunals which will take a year or, according to some estimates, 10 years to complete the process.

Nitin Sethi, founder of Reporters’ Collective, which has conducted several forensic examinations of SIR since it was first conducted in Bihar from June 2025, said in a statement on Wednesday: 'If you are reading others on this (the impact of SIR on Bengal results), I would advise you to consider if the following have been parsed and factored in:

1. The 2025 or previous voter lists, the historical and accumulated problems in that and the patterns of those problems.

2. The actual process of how deletions, detection of doubtful voters through the software happened at different states (and it did keep on changing).

3. Overlap this with the organic voter shift in favour of BJP.

4. Actively avoiding confirmation bias while building assumptions and conclusions drawn from correlations.

'I am yet to see any cogent argument or reportage that acknowledges taking these four into account while concluding, by allusion or directly, how significant SIR's impact is on any party's votes in the state in a quantifiable manner across the state.

'That said, the SIR, as done in West Bengal and largely condoned by SC (in fact, enabled by it), regardless of how it impacted any political party's fortunes, is a dangerous and deeply worrisome precedent for voters and citizens in India. It sets a paradigm that endangers the fabric of electoral politics, democratic integrity, and citizen right in India. Regardless of who the voter today or tomorrow votes for.'