Indian security personnel carrying batons and shields and accompanied by riot control vehicles surrounded the site of a planned opposition protest in Delhi on Sundaym with the protesters set to ​demand the resignation of the country’s election chief over a controversial revision of voter lists.

Authorities ‌warned of traffic diversions ahead of the protest march and rally that will be led by Congress party leader Rahul Gandhi. The opposition says it expects hundreds of thousands of people to participate in what it says will be a major ​challenge to Prime Minister Narendra Modi and his Bharatiya Janata Party (BJP).

Opposition parties, student organisations and the youth-led Cockroach ​Janta Party have held near-daily demonstrations since last month demanding that Chief Election Commissioner Gyanesh Kumar ⁠step down over the voter list revision that critics say favour the BJP.

The Election Commission has denied favouring ​any party and said wrongly deleted voters can re-enrol, while the BJP has accused rivals of trying to ​undermine democracy by wrongly questioning legitimate electoral processes.

Analysts say the youth protests, and growing support for the opposition, form the worst crisis for Modi since he came to power in 2014. But his government remains stable and the next general election is not ​due until 2029.

The opposition parties have announced they will hold a nearly 1.5 km march on ​Sunday from Central Delhi to the Ramlila Maidan, a ground that is the designated site for their protest rally.

Visuals from news ‌agency ⁠ANI showed riot control vehicles and dozens of security personnel armed with batons and shields outside the rally venue, where announcements were being made urging people to ensure smooth traffic movement and cooperate with police officials.

Delhi Traffic Police said “a large gathering” was expected at the venue, and traffic regulations and diversions would be implemented “as required”.

“People ​have started coming to ​participate in this rally … we ⁠have ensured proper arrangements at the venue, and arrangements are also planned on the route of the march that will happen in a few hours from now,” senior ​police officer Rohit Rajbir told ANI.

The protests demanding Kumar’s resignation erupted after The ​Indian Express ⁠newspaper reported in September that his two deputies had raised several concerns internally about voter list revisions, registration procedures, and digital systems.

The change, which began last year, removed over 130 million names — more than the population of Japan — from ⁠voter lists, ​including 28m who died, 63m who relocated, and 30m who could not be traced.

Opposition parties allege the deletions disproportionately affect Muslim voters and other minorities, who are unlikely to support ​the Hindu nationalist ruling party — allegations the poll panel and BJP reject.