Banerjee, who is seeking a third term, left the Bhabanipur constituency in Calcutta to fight from Nandigram, the epicenter of an anti-land acquisition movement that catapulted his ruling party in 2011, ending the reign of 34 years of the Left Front.
Exit polls predict close competition between the ruling Trinamool Congress and the BJP in eight-phase elections to the 294-member assembly.
The count will decide the electoral fate of 2,116 candidates, including candidates from the Left-Congress-Indian Secular Front alliance.
The exercise is underway in 108 counting centers in the 23 districts of the state, where a three-level security system has been put in place.
At least 292 observers have been appointed and 256 companies of the central forces deployed in the counting centers. The 292-seat assembly ballot took place in eight phases from March 27 to April 29. Voting at Shamsherganj and Jangipur headquarters in Murshidabad district has been postponed due to the deaths of some candidates. The ballot for these two seats will now take place on May 16 and the votes will be counted on May 19.
(With PTI entries)