Teachers from the UNO Charter School Network, one of Chicago’s largest charter school systems, voted overwhelmingly Thursday in favor of a strike if workers and management don’t reach an agreement before Oct. 19.

The vote was nearly unanimous, with 531 of 532 members of UNO’s unionized workforce voting, and 96 percent of those ballots cast in favor of striking if workers can’t come to a fair agreement with management by Oct. 19, the day set for a walkout by UEU, the United Educators of UNO, according to spokeswoman Erica Stewart, a fifth-grade teacher at the Sandra Cisneros UCSN campus in Brighton Park and a member of the bargaining team.

The strike would be the first in U.S. history of a charter school or charter network.

If teachers at the 16-school network walk out, they’d likely be the nation’s first group of charter school educators to do so.

“We took this historic vote to show management that we are willing to go to great lengths to insure that our students have the best opportunities for a great education,” Stewart said in a statement. “Our members have overwhelmingly voted to send a strong message to management that they need to step up and do the right thing for our kids and our schools. Now it’s management’s turn to show their dedication to the employees they claim to value — and the students whose lives are in their hands.”

Stewart said that negotiations over the teachers’ second contract with the charter chain have gone on for seven months.

The union is looking for a slightly longer summer than the current five weeks off. It wants six weeks and two days.

It also is asking management to cap class sizes at 32 students.

And though teachers at UCSN campuses fare well financially in management’s proposals, support staff do not, Stewart said.

A Sept. 30 statement posted on the network’s website from UCSN CEO Richard Rodriguez said “there is no need for a strike, as teachers have already received their salary raises for this current school year.”

On average, teachers got a 6.2 percent raise, or about $3,822 per teacher. That’s despite a $5.7 million cut in the funding CPS sends to UCSN.

“No one wants to go on strike,” Stewart told the Chicago Sun-Times. “We don’t want to do that to our families, we don’t want to do that to ourselves, but we’re getting to a point where management is pushing us into a corner.”