Police have arrested journalists, shut down the internet and targeted the social media accounts of protest groups and independent media in response to the gatherings. They have also blockaded central Delhi and detained demonstrators to prevent groups from assembling in one location. The detentions have triggered accusations that Prime Minister Narendra Modi's government is stifling dissent.
The rallies are being spearheaded by the opposition Congress party, the All India Students Association and the Cockroach Janta Party (CJP), and organisers say they are likely to have a long tail.
The dispute dates to June last year, when the Election Commission announced it would revise its Special Intensive Revision (SIR) process in Bihar ahead of the state election. The SIR, which dates to the 1950s, was a relatively routine exercise to keep electoral rolls up to date by removing deceased voters, duplicate registrations and ineligible entries.
The commission changed how voters were verified, requiring anyone enrolled to vote after 2003 to provide documents proving their date and place of birth. The revision has since been running for more than 18 months and now covers most Indian states.
Critics allege the mass deletion of names includes many people who are not typical BJP voters, and that the new requirements place a disproportionate burden of proof on migrants, elderly voters and millions of Indians living in poverty who may struggle to find family records. Congress leader Rahul Gandhi last year called the SIR "a new weapon for vote theft".
The Election Commission has said its draft roll and corrections are being made to include eligible voters.
Kumar, a 62-year-old career bureaucrat, was controversially appointed chief election commissioner in February last year. He is one of three election commissioners overseeing India's elections.