Polling began for 30 seats in West Bengal and 47 seats in Assam at 7 am on Saturday in the first phase of the assembly elections amid tight security. West Bengal will witness a triangular contest between Trinamool Congress (TMC), Congress-Left alliance and Bharatiya Janata Party (BJP). In Assam, candidates from BJP and Congress-led 'mahajot' (grand alliance) are in fray.