CHICAGO (CBS)–Chicago Teachers Union educators at Acero Charter Schools will likely strike, following a an overwhelming vote of support Tuesday in support of a walkout.

The teachers could announce a definitive strike date this week after 98 percent of the unionized teachers who turned out to vote Tuesday said they supported a a strike.

Chicago Teachers Union reps have been in talks for better classroom resources, more diversity, additional special education staffing, sanctuary schools and more pay, according to a statement from the union.

The union represents 536 employees at Acero’s 15 schools, according to a press release.

Acero is the largest unionized charter-school operator in Chicago Public Schools. Acero’s teachers’ contract expired Aug. 2 and was extended until Oct. 3.

Educators at four unionized charter schools will take a final vote on whether to strike on Friday.