Mayor Lori Lightfoot said Thursday she’s willing to consider compensating teachers for days spent on strike, but only if the Chicago Teachers Union calls her first and moves away from its “take-it-or-leave-it” demand that all 11 days be made up.

On Wednesday night, Lightfoot appeared to draw a line in the sand by declaring, “I’m not compensating them for days that they were on strike.”

After sleeping on it, the mayor changed her tune.

“We have been told by the CTU that they will end the strike only if we agree to make up all the days missed due to the strike. They have basically issued a take-it-or-leave it demand: They get 11 days back or the strike continues. That’s simply a nonstarter,” the mayor told a City Hall news conference Thursday morning.

“Negotiations are about good faith. And both sides must have a spirit of compromise. ... If the CTU wants to have a conversation in that spirit of compromise, then of course I’m willing to listen. ... What I’m not willing to do is a take-it-or-leave-it, unilateral demand, which is what they’ve given.”

The mayor refused to say where the middle ground might be or whether she was willing to convert institutional days into instructional days. That would be a way of making up strike days without additional compensation for teachers, since they are paid for instructional days without students.

Lightfoot said she would not negotiate in public. Nor would she make the first move.

“They gave us a unilateral, take-it-or-leave-it demand. I think the ball’s in their court. I’m here all day. I’m gonna be working and continuing the business of the city. If they’d like to have a conversation, they know how to find me,” the mayor said.

The mayor once again accused CTU President Jesse Sharkey of “moving the goal posts.”

Lightfoot said Sharkey didn’t mention compensating teachers for days spent on strike during their hourslong negotiating session in the mayor’s office.

“If there was some urgency and other issue — particularly in the context of me saying repeatedly from Day One that I was not going to pay them for [the] strike, that we were not gonna make up these days — wouldn’t you think ... they would have brought it to the table? They didn’t do that. ... If they’re willing to come to the table in a spirit of compromise, I’m certainly willing to listen. But, this is on them.”

Schools CEO Janice Jackson said making up strike days is not as simple as it sounds.

“We’re on Day 11. In order to make that up, there’s really no way to do that, except to tack it on at the end of the school year or take away winter break. These are two periods of time where we know families have already made arrangements. Children won’t be present. Many of our teachers won’t even be present on those days,” Jackson said.

“We’re talking about an institutional structure that we’re trying to preserve. This year has already been disrupted because of the strike....The only way to make up eleven days is to really disrupt families’ plans that have already been made.”

Lightfoot said the city has already talked to the Illinois State Board of Education and CPS is “well within where we need to be” without making up any strike days. The mayor insisted that no money would be lost.

Ald. Michael Scott Jr. (24th), chairman of the City Council’s Education Committee, said the mayor wants to get kids back into the classrooms.

“If that means negotiating the number of days, that’s what it is,” Scott told the Sun-Times. ”They came to her with 10 days or nothing. It’s not 10 days or nothing. It’s negotiating.”