Prime Minister Narendra Modi will launch his poll campaign in Bengal today with two mega rallies - the first in north Bengal's Siliguri and then at the historic Brigade Parade Ground in the heart of Kolkata. The BJP is hoping for an audience of eight lakh at the Brigade Parade ground, where the opposition's Mahagathbandhan was born with a rally organised by Chief Minister Mamata Banerjee in January. The fight is over the state's 42 seats, of which the BJP is targeting more than 20. The BJP, which practically had no footprint in the state, has made inroads, with its vote share ticking steadily upwards. But so has the Trinamool's, with the CPM and Congress losing supporters.