CHICAGO (CBS) — As the Chicago teachers’ strike enters its third day, Mayor Lori Lightfoot said she hopes to “continue to see some progress” in negotiations, but she also cast doubt that students would return to class on Monday.

At a news conference, Lightfoot said both sides had resumed talks Saturday afternoon.

“We’ve got to be at the table to get a deal done,” she said. ‘That’s why we continue to press for lengthly negotiations, seven days a week.”

When asked if there was a possibility of classes resuming Monday, Lightfoot said: “I would be very surprised if classes were opened on Monday, but we will check in with CPS and get the word out one way or another.  My expectation is that we will not be back in class on Monday.”

The mayor’s office told CBS 2’s Marissa Parra the decision on Monday’s classes should be announced by Sunday afternoon.

In response to questions about the negotiation’s late start today, the union’s general counsel Robert Bloch said, “Just because we’re not at the table together doesn’t mean we’re not working on our proposals … and that work has been going on all day on both sides as far as I know.”

Beyond a disagreement about salaries, CPS and CTU are at odds about staffing issues, class sizes, and other matters.

CPS has been offering the union a 16% total raise over the life of a five-year contract, while CTU has called for a 15% total raise over a three-year deal — a shorter contract, with higher average raises per year.

The union also is demanding increased staffing of nurses, social workers, librarians, clinicians, and case managers. CTU has said it might be open to phasing in more of those staff, but the two sides couldn’t reach an agreement on how to do so before the strike deadline.

Teachers also have demanded contract guarantees to reduce class sizes. They say 1,300 classrooms are overcrowded. At the elementary level, they want student counts to be limited to maximum of 24.

The mayor’s office has said the city’s latest proposal earmarks $1 million to ease overcrowding, but the union has said that would fund no more than 25 new teachers for the entire district.