Chief minister of West Bengal state and supremo of Trinamool Congress (TMC) Mamata Banerjee (C) along with other leaders gesture during a mass meeting in Kolkata on January 19, 2019. India's opposition parties drew half a million supporters to Kolkata's streets on January 19 for the largest show of force yet against Prime Minister Narendra Modi as a national election looms. / AFP / STR
Mamata Banerjee, centre, and other Indian regional party at an opposition rally in Kolkata on January 19, 2019. AFP

India opposition parties prepare mega-coalition to defeat Narendra Modi's BJP