India’s main opposition parties joined forces against Prime Minister Narendra Modi at a rally in Kolkata on Saturday which attracted hundreds of thousands of people months ahead of elections.

The 23 regional groups said they forged a common front to stop Modi’s Hindu nationalist Bharatiya Janata Party, which beat the main opposition Congress and regional parties in 2014.

Addressing the rally, Chief Minister of the state of West Bengal, Mamata Banerjee called on regional party leaders to join a single platform to defeat the anti-people government of Modi, which is nearing its end.