Trinamool Congress supremo Mamata Banerjee on Saturday appealed to all opposition parties in West Bengal to come together to form a "joint platform" to fight the BJP which came to power in the state after the recently held assembly elections. The former chief minister also called upon the student unions of various affiliations opposed to the BJP and the NGOs to unite against the saffron camp. "I call upon all opposition parties, including the Leftists and the ultra-Left, to come together to form a joint platform against the BJP," Banerjee said, also calling upon national parties to join.