West Bengal Chief Minister Mamata Banerjee sat overnight in front of Dalit icon Dr BR Ambedkar's statue on Red Road in the heart of the city, surrounded by a cohort of TMC leaders and workers under television camera arclights. The chief minister who is staging a two-day-long sit-in to protest alleged discrimination by the centre against the state, had Wednesday in a change of stance urged all political parties in the country to unitedly fight the BJP in next year's Lok Sabha election, in a departure from an earlier decision to remain equi-distant from both the Congress and the right-wing party ruling India's federal polity.