Chicago’s mayor rejects union’s terms for returning to school.

A labor standoff between Chicago educators and Mayor Lori Lightfoot showed no signs of abating over the weekend, as the mayor swiftly rejected a proposal by the teachers’ union to ramp up coronavirus testing and return to in-person instruction on Jan. 18.

“The best, safest place for kids to be is in school,” Ms. Lightfoot and Pedro Martinez, the Chicago Public Schools chief executive, said in a joint statement on Saturday. “Students need to be back in person as soon as possible. That’s what parents want. That’s what the science supports. We will not relent.”

Ms. Lightfoot’s and Mr. Martinez’s sharp retort, which also accused labor leaders of “not listening,” came minutes after the Chicago Teachers Union announced a proposal for a return to classrooms that it framed as a compromise. In it, the union dropped demands for all students to produce negative tests before coming back to class, and said teachers were willing to return to school buildings starting on Monday, though not for in-person instruction.

“This represents a change in our position,” Jesse Sharkey, the union president, said at a news conference on Saturday. “We’re appealing to the public — and to the mayor to find in her heart to make the compromise to reopen the schools.”

Hundreds of thousands of students in the nation’s third-largest school district missed three days of class last week after members of the Chicago Teachers Union voted to stop reporting to work amid concerns over the rapidly spreading Omicron variant.

School district officials, who have insisted that classrooms are safe, declined to move to online instruction, as the union suggested. Ms. Lightfoot has repeatedly accused the union of inconveniencing working families and harming the academic and social progress of children.

Most American school districts have forged ahead with in-person instruction, as the Biden administration has urged, even as the Omicron variant has shattered local and national case records. Some large school districts, including in Cleveland and Milwaukee, have moved classes online. But the dispute in Chicago, where there has been no instruction of any sort since class was dismissed on Tuesday, has been notable for its acrimony and for the day-to-day uncertainty for parents, teachers and students.

Under the plan the union outlined on Saturday, Chicago teachers would have distributed equipment and materials for online instruction and helped parents sign up for virus testing on Monday and Tuesday, then taught students remotely for the rest of next week.

The union had already said that members planned to return to schools on Jan. 18, after Martin Luther King Jr. Day, a date that did not change under the new proposal. The union also continued to push to have all children enrolled in Covid-19 testing unless their parents opted them out, a move that Ms. Lightfoot has opposed. Currently, students are tested through the schools only if parents proactively give permission.

“The mayor can’t be, like, a hard no and morally opposed to widespread testing,” Mr. Sharkey said, “and also be a hard no and be morally opposed to any short-term period of remote.”