 When the city would not agree to the CTU's core demands, including an expansion of programs like art and music at the city's most underfunded high schools, CTU members voted overwhelmingly (90% of teachers and 98% of those who cast ballots) to authorize a strike.On September 10, 2012, the Chicago Teachers Union began a strike after CTU President Lewis declared that negotiations with the city were not succeeding.This strike was the CTU's first since 1987, and the first strike ever for many of the teachers involved.