Indian security personnel carrying batons and shields and accompanied by riot control vehicles surrounded the site of a planned opposition ⁠protest in Delhi on Sunday that is 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 the 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 the chief election commissioner, Gyanesh Kumar, step down over the voter list revision that critics say favours 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 1.5km 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 from voter lists, including 28 million who died, 63 million who relocated and 30 million 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.