(CNN) -- With a strike potentially just hours away, Chicago school officials met again Sunday, September 9th with teachers' union representatives in hopes of coming to an elusive contract agreement.
Teachers and support staff in the 30,000 member union have set a walkout date of Monday, which would mark the first time workers for the third-largest public school system have gone on strike in 25 years.
On Sunday, Chicago Teachers Union chief Karen Lewis told CNN that there was positive movement on at least one issue during the previous day's talks.
"On the pay issue, we've had some progress as of yesterday for the first time. It's sort of annoying that we have to wait until the 11th hour to get these kinds of issues done," she said.
Just as she'd stated Saturday night, Lewis said no action has been taken to alter the teacher's plans to strike starting Monday.
"I am certainly hopeful that we can come to some sort of understanding and agreement," she said. "But if not, our members are prepared for tomorrow."
In June, the teachers' union voted to authorize a strike, and they have continued negotiating with the board since.
On Saturday, the president of Chicago's board of education told reporters he felt progress was made in extensive talks that day, while noting the pressure posed by the fast approaching deadline.
"We've got parents and children who are wondering what's going to happen to them Monday morning," said David Vitale. "We have an obligation to them to tell them what's going to happen. And we really want to get this work done."
If a strike happens, it would affect nearly 700 schools and about 400,000 students, including some from neighborhoods struggling with crime and gang problems.
For them, that would mean the school year would abruptly stop soon after it started: Some students in the district began class on August 13, and more -- on a different schedule -- started on September 4.
Vitale said the school system on Saturday presented the union with an "updated proposal" from one submitted two days earlier that takes into account the union's concerns on issues such as salaries, merit pay and health care. Lewis told CNN the issue of teacher evaluations was also critical.
"We have moved dramatically on almost all these issues to try to accommodate them and to respect our teachers," Vitale said, noting that there have been "well over 100 meetings" over eight months of talks. "This is a proposal that we believe is very close to what is needed to do a deal."
Vitale said Saturday night he was "still optimistic that our children will be in school on Monday morning."
"We have high hopes that we can get back to tomorrow, we can move to the end game," he said.
Lewis, from the teachers union, said that she wouldn't characterize the school system's movement as "dramatic," saying only "they are starting to talk about the ... issues that we are most concerned about" like pay, benefits and job security.
Teachers are tired of "being told to sit down and shut up," Lewis added, claiming parents are "extremely supportive" of their cause and blaming part of the situation on Mayor Rahm Emanuel, who took office in May 2011.
"We've had a mayor who has been determined to silence the voices of the people who do this work," she said of Emanuel, a former U.S. congressman and White House chief of staff.
CNN affiliate WLS-TV reported that teachers were told Sunday that picket lines would form at 6:30 a.m. CT (7:30 a.m. ET) Monday.