CHICAGO – The vice president of the Chicago Teachers Union said Saturday the city school district’s latest offer in contract negotiations was disappointing and that the wrangling would continue throughout the weekend, as tens of thousands of teachers readied to walk off the job Monday.

Chicago teachers say they’re prepared to walk off the job for the first time in 25 years over issues that include pay raises, classroom conditions, job security and teacher evaluations. A strike would cause massive disruptions in the nation’s third-largest school district, which has 400,000 students.

Both sides met Saturday to try to close the remaining gaps, but union Vice President Jesse Sharkey told reporters about an hour into the talks that there was more work to be done because the district’s latest proposal fell short.