NEW DELHI, Nov 21: The controversial “Special Intensive Revision” (SIR) exercise of the voters initiated by the Election Commission of India (ECI) in Bihar, does not seem to have played a determining role in the ruling National Democratic Alliance’s (NDA) massive victory in the just-concluded state Assembly elections, a data-driven analysis comparing changes in vote share patterns with the extent of electoral roll deletions across assembly constituencies suggests.
The SIR process just before the elections had become one of the most contentious issues in Bihar with accusations and counter-accusations flying between the NDA and the opposition Mahagathbandhan. The BJP and its allies welcomed the process as necessary to remove “infiltrators” from voter lists, while the Congress and Rashtriya Janata Dal (RJD) decried it as systematic disenfranchisement—part of what they termed “vote chori,” or vote theft, alleging collusion between the ECI and the ruling BJP to “manipulate” electoral rolls in the latter’s favour.
The controversy wasn’t confined to campaign rhetoric. The SIR process also required multiple interventions by the Supreme Court including orders to publish reasons for the deletion of names from the draft electoral roll and permission for electors to use Aadhaar as the 12th identity document for enrolment. The scale of the revision was unprecedented: approximately 68 lakh electors were deleted from Bihar’s electoral rolls, while 24 lakh were added, resulting in a net deletion of around 44 lakh voters between January 2025 and October 2025.
The electoral outcome itself showed remarkable continuity with the 2024 Lok Sabha elections. The NDA secured close to 46.6% of the vote share in the Assembly polls, a marginal drop of around 1.4 percentage points from the parliamentary elections held in May 2024. The Mahagathbandhan’s vote share declined more sharply, falling by approximately 2.2 percentage points from 39.2% to 37%. While these shifts favoured the NDA, the pattern suggests the alliance retained rather than expanded its existing advantage over the opposition.
Analysis of two key variables across Bihar’s Assembly constituencies showed the change in the vote share difference between the NDA and MGB from the 2024 Lok Sabha elections to the 2025 Assembly elections, and the decrease in electorate numbers following the SIR as a percentage of the original electoral roll.
The conclusion was straightforward: there was no major increase in NDA vote shares relative to the decrease in the electorate across Bihar. The NDA’s advantages from the 2024 Lok Sabha elections remained largely intact, and the coalition’s victory appears to have been based on the same factors that gave it an edge in the parliamentary polls rather than being a product of the SIR process.
However, it would not diminish the concerns about the SIR process. Data also revealed that there was a disproportionate decrease in the number of women in the electorate following the SIR leading to the gender ratio dropping from 907 in the January rolls to a meagre 892 in the final rolls released in September. And yet women turned out in much larger numbers compared to men (four lakh more despite being forty lakh fewer in the rolls).
However, the data also suggests that the SIR, despite being a major political flashpoint and campaign issue besides being a flawed administrative step, did not alone determine the outcome of Bihar’s 2025 Assembly elections.
(Manas Dasgupta)