The BJP has fielded lawyer Priyanka Tibrewal against Bengal Chief Minister Mamata Banerjee in the September 30 Bhabanipur bypolls. Ms Tibrewal was one of the petitioners in the Bengal post-poll violence case. Mamata Banerjee, who took charge as Chief Minister for the third time after the Trinamool Congress's mega victory in the election, needs to win the bypoll to retain the top post.