NEW DELHI — Protests have spread across India as opposition parties and civil society groups call for Chief Election Commissioner Gyanesh Kumar to resign and demand a halt to a nationwide review of voter lists. The demonstrators say the process could remove millions of eligible voters; the Election Commission and the government deny wrongdoing and say the review is intended to clean up the rolls. The review, known as the Special Intensive Revision, began in Bihar last year and has since expanded to most Indian states and federally administered territories. Voters are being asked to provide documents establishing their eligibility to remain registered. Critics say the requirements can be confusing and difficult to meet, particularly for poorer people and others without older government records. The dispute is especially consequential in India, the world’s largest democracy, where the Election Commission oversees elections and determines who is eligible to vote. Opposition parties accuse the commission of favoring Prime Minister Narendra Modi’s Hindu nationalist Bharatiya Janata Party, arguing that the revisions could disproportionately remove voters likely to support its opponents. The BJP and the commission reject that allegation. The party has said the review will weed out what it calls “infiltrators.” The stakes were highlighted in West Bengal, where a voter-list revision removed about 9 million names — roughly 12% of the electorate — ahead of state elections earlier this year. The deletions left millions of eligible voters unable to cast ballots, according to the account of the election. Modi’s party won the state for the first time. In Mumbai on Sunday, Oct. 4, protesters organized by Shiv Sena (UBT) and the Maharashtra Navnirman Sena called for Kumar’s resignation and suspension of the review. The campaign is also backed by the youth movement known as “Cockroach,” which previously organized protests that led to the education minister’s resignation in July. Opposition parties and civic groups are seeking an inquiry into Kumar’s conduct, including possible criminal proceedings, and want earlier voter lists used in future elections. They are also calling for a more independent and transparent system for appointing election commissioners. The groups cite Election Commission data indicating that voter rolls in some regions could shrink by as much as 30% under the revisions. The commission’s internal decision-making has also drawn scrutiny. Indian law requires a majority vote by commission members for changes. The Indian Express reported in September that two of the three election commissioners had formally objected to decisions concerning voter-list revisions, registration procedures and the commission’s digital systems, and that Kumar rejected their objections. The commission characterized the reported dispute as differing views and deliberations, rather than formal written objections. The controversy is likely to sharpen as the revised rolls take effect and India approaches a series of state elections early next year. For critics, the central question is whether a process intended to verify voter eligibility can be carried out without barring eligible citizens from the ballot.