Did SIR exercise win West Bengal for the BJP?

THe unawares respond: potential non.For the long reply: read on.The question above is the most polarising one to ask vis-à-vis the West Bengal results. Of the 14 states and union territories where the Election Commission of India (ECI) has conducted the Special Intensive Revision (SIR) or special revision (SR) of electoral rolls since last year, six states/UTs have had elections after the exercise. SIR was the most contentious and potentially disenfranchising in nature in West Bengal, where 2.7 million electors were removed from the rolls under the adjudication process (and were awaiting their fate even on the day of election) over and above the 6.2 million who were deleted in SIR apart from the adjudication category.SIR’s constitutional and political morality problems aside, it could not have won the Bharatiya Janata Party (BJP) the state of West Bengal if hard electoral data is looked at. Here is why.The BJP and the All India Trinamool Congress (TMC) (both are taken along with any allies throughout this analysis) have vote shares of 45.8% and 41.1% respectively in the 2026 assembly elections as of 10pm.Also Read: Key takeaways from the election results | Number TheoryThe BJP has gained 7.1 percentage points in vote share and the TMC has lost 4.7 percentage points compared to the 2024 Lok Sabha elections, the latest pre-SIR poll in the state. In absolute terms, the BJP has polled 5.6 million more votes while the TMC has polled 1.7 million less votes compared to the 2024 elections (according to ECI data as of 10pm). The net SIR deletions in the state are 8.9 million, of which 2.7 million were deleted during the adjudication process. That the decline in votes polled by TMC is close to at least the adjudication deletions makes it tempting to believe that SIR could have played a role in the BJP’s victory in West Bengal, as indeed some analysts have claimed. But did it really? Answering this question requires reading the numbers in context.Let us look at them one by one.Decoding SIR's impact outside party strongholdsThe TMC and allies had won 226, 211, and 215 assembly constituencies (ACs) in the 2011, 2016 and 2021 assembly elections in West Bengal. It won 124 ACs consistently in all three of these elections. Because AC boundaries were changed in the 2008 delimitation, it is impossible to factor in pre-2011 elections for this analysis.Also Read: Decoding what swung the votes in Bengal, Tamil Nadu, Kerala and AssamIn 2026, the TMC and allies have lost 78 of their 124 stronghold ACs (election has been postponed in one of those 124 ACs) and won just 34 outside this group of ACs.The BJP, won 121, 77, and 90 ACs in the 2019, 2021 and 2024 elections, if one were to break up 2019 and 2024 Lok Sabha results into AC-segments. It won 54 ACs in all of these elections. In 2026, the BJP has won all of the 54 ACs it won in 2019, 2021 and 2024 elections. It won 100% of the 142 ACs it won in any of these elections. And it added another 65 ACs to its kitty which it had never won. If one has to really understand the reversal of political fortunes in the state, one ought to examine SIR’s impact on the state’s election results excluding the 100 stronghold ACs which have stayed with the TMC and the BJP in 2026.How many of these ACs saw an absolute fall in turnout between 2024 and 2026? This is an important question to ask because SIR did not lead to an absolute fall in voter turnout between the pre- and post-SIR election in West Bengal, which is what has also been the case in all states that have had SIR and elections.The answer to this question is 20 out of 100 (13 the BJP has won continuously in 2019, 2021, 2024 and 2026; and seven the TMC has won continuously in 2011, 2016, 2021, and 2026) as of 10pm.What about the extent of voter deletion in these ACs due to SIR? The range is from just 2.1% to 38.6% with a median value of 9.5%. However, when it comes to tracking the change in vote shares of either the TMC or the BJP along with share of SIR deletions, there seems to be next to no correlation between the two. (See Chart 2A and 2B) SIR’s impact on Muslim votesWhat about the impact of communally biased deletions under SIR? The most damning indictment of the SIR process, rather its adjudication phase in West Bengal was the disproportionately high share of deletions in the adjudication phase in districts which have a higher share of Muslim population in the state.West Bengal had 39 ACs which had elected a Muslim MLA in 2011, 2016 and 2021 assembly elections. 18 out of these 39 ACs were in districts which had a Muslim population share of 50% of more according to the 2011 census. 34 of these ACs have elected a Muslim MLA this time as well. Five of them are actually non-TMC candidates.The BJP has won the remaining five. In three of these, another Muslim candidate played spoiler for the TMC.The number of Muslim MLAs in the new West Bengal assembly is 40. This is broadly the same as in 2021. However, the share of Muslim MLAs in the TMC’s legislative group has increased to 42.5%.This is a classic case of communal polarisation – similar to what the Congress has been facing in Assam – rather than a direct fallout of gerrymandering of electoral rolls. The political trend of rising share of Muslim MLAs for the Congress in Assam predates delimitation and Special Revision of rolls. (See Chart 3) So what really won West Bengal for the BJP?The answer is an extremely powerful anti-incumbency wave which has communal polarisation tailwinds. Between 2021 and 2026, the TMC has lost vote share in 268 out of the 293 ACs for which votes were counted yesterday. In 69 of these it has lost more than 10 percentage point in vote share. The BJP has gained vote share in 270 out of 293 ACs and more than 10 percentage points in 95.What does such a large shift in popular support entail? A historical comparison can help put things in perspective.The Communist Party of India (Marxist) led Left Front lost almost 11 percentage points in vote share between its thumping victory of 2006 of the crushing loss of 2011.While an AC-wise mapping of the swing is not possible because of delimitation changing AC boundaries, TMC’s overall vote share loss of almost 4.7 percentage points in 2026 is relatively small compared to the Left Front’s.This is why it has managed to preserve its seat share at a much higher level than the Left in 2011.The TMC’s bigger problem still awaits it. What if it sees an exodus of the remaining Hindu voters it still has, either to the BJP or to other opposition parties in the state, who will definitely mount a huge criticism of the TMC now that it has lost to the BJP. Politics is far from over in West Bengal.