CHICAGO — Teachers and Chicago Public Schools officials remained deadlocked Monday over a plan to broadly resume in-person instruction, with the two camps at an impasse over how to assuage teachers' pandemic-related safety concerns by Wednesday, when the next large group of teachers and staff are to report to their schools.

The nation’s third-largest school district, backed by Chicago Mayor Lori Lightfoot (D), has insisted its reopening plan is safe — noting the $100 million in health and safety upgrades — with Lightfoot telling reporters during a news conference Monday that in-person instruction for prekindergarten classrooms has been without incident since it began two weeks ago.

Amid the back-and-forth, both camps made efforts to avoid addressing head-on the looming possibility that the impasse could escalate into a strike.

Lightfoot said she had “productive conversations” with the Chicago Teachers Union over the weekend and has confidence “we will get something done that obviously protects their members but also gives families the options if it’s right for them to be able to send their children back to in-person learning.”

Thad Goodchild, deputy general counsel for the union, said all the union’s leadership and members want in-person learning to resume, as long as it can be done safely.

“There is an obvious agreement to make that happen,” Goodchild said.

The Chicago Teachers Union has balked at the district’s plan to force teachers back into classrooms before they can be vaccinated and have challenged the district’s claims of health and safety preparedness by noting that many CPS schools were under-resourced before the coronavirus pandemic forced them to close last March.

The struggle over resuming in-school instruction has escalated since some pre-K classes reopened on Jan. 11. Many teachers protested their workplace conditions amid the pandemic and opted to continue remote instruction, either on school grounds but outside the classrooms or from their homes. Some instructors, however, found themselves locked out of their virtual teaching platforms after refusing to show up for in-person classes.

As of Jan. 16, the district had started disciplinary proceedings against more than 100 district employees.

On Monday, Illinois entered its next phase of vaccinations for the coronavirus, making them available to essential workers, teachers and adults over the age of 65. Pending the vaccination of every instructor, the union proposed only staffing schools with educators who voluntarily return in person. It argued that requiring all teachers to return was unnecessary because fewer than 20 percent of students had returned for in-person instruction.

“What Chicago Public Schools is asking educators to do is like asking someone to jump out of the plane holding a blanket while a parachute is a few rows back,” Goodchild said.

A key sticking point in negotiations has been expanding what criteria the district uses for granting medical accommodations. CPS spokeswoman Emily Bolton said Monday that the district grants “all ADA medical accommodations.”

Dawn Kelly, a special-education teacher at Carrie Jacobs Bond Elementary School in Chicago’s Englewood neighborhood, applied for a medical accommodation for her chronic hypertension. Kelly said she was locked out for over a week from teaching her students remotely, until the district reversed course and approved her accommodation.

“My families were devastated,” Kelly said. “They had no one to cover my class and I was sitting in front of a computer. Why couldn’t I access my children? We really need to be mindful at this moment in time of how we’re moving forward.”

CTU Vice President Stacy Davis Gates on Monday framed reopening schools not just as an issue of safety, but one of racial justice in a district that serves predominantly Black and Latino students, many of whom come from low-income households.

“Let me tell you what kids will be going back into buildings with: There is not a nurse in every school … there is not a social worker in every school. We’re in the middle of a pandemic where students have lost people who are close to them,” Davis Gates said.

“Don’t just tell me you can return Black and Brown children who are in pain back into a building that does not — has not — had the things they’ve needed for a very long time to meet their needs.”

Davis Gates noted that while the district is demanding teachers return to the classroom by Wednesday, only 19 percent of students showed up for in-person learning when the district resumed in-person instruction for pre-K students earlier this month.

Public schools in Chicago have largely remained closed since last spring when the first wave of the coronavirus pandemic took hold.

The district pushed its Jan. 25 deadline for the return of K-8 staff and teachers to Jan. 27 after a majority of the union’s more than 25,000 members voted over the weekend to defy the district’s order and continue with remote learning.

By Monday evening, neither the CTU nor CPS would offer concrete details on the status of negotiations. Both sides simply said they were “in process” or “ongoing” — though CTU President Jesse Sharkey told reporters on a call that “there are some hard parts” involved in the discussion.

The union’s plight received a boost Monday afternoon when President Biden made remarks during a White House briefing in Washington that the union quickly embraced as supporting its position.

“We should make school classrooms safe and secure for the students, for the teachers and for the help that’s in those schools maintaining the facilities,” Biden said when asked about the CTU’s situation and whether he thought teachers should return to classrooms.

Biden has made reopening the majority of K-8 schools within the first 100 days of his presidency a top priority, but Chicago teachers welcomed his emphasis on safety for students and teachers.

Shavon Coleman, a prekindergarten teacher assistant at Lawndale Community Academy on Chicago’s West Side, thanked Biden for “hearing and expressing” what teachers have been asking for over the past several months: proper ventilation, adequate personal protective equipment and protocols for handling a coronavirus outbreak.

“Someone heard us,” Coleman said during the union’s news conference. “And that means everything.”