Mamata Banerjee has said it many times before. But today, after the Trinamool clean sweep at Maheshtala, her two word slogan has become a war cry: Dilli Chalo. The Trinamool chief and proponent of the federal front repeated her formula of regional parties uniting, with the Congress, where it is a factor, and taking on the BJP. The Uttar Pradesh results today, she said, was a signal of the beginning of the end.