The Chicago Teachers Union voted on Wednesday to pull its support of education reform legislation before the Illinois House if a section on collective bargaining was not revised. The union initially endorsed the the education reform bill, which was passed by the Illinois Senate and is currently before the Illinois House. Robert Bloch, a lawyer for the union, said a two-sentence section of the bill, SB 7, was an “atomic bomb” that took some of the teachers’ collective bargaining rights. The union said the language was added to the bill at the last minute and was not among the original provisions that the union endorsed.