New York City’s teachers’ union is intensifying pressure on Mayor Eric Adams to deliver raises, signaling what could be a thorny challenge for the mayor as he contends with expired contracts from nearly all of the city’s municipal unions.

“Right now, I don't think the city is prepared to actually give all city workers the raises they deserve,” said Michael Mulgrew, the president of the United Federation of Teachers, which represents 120,000 workers currently employed by the Department of Education, during a phone interview on Tuesday.

“I think you're going to have to see some friction,” he added. The contract for the teachers’ union expired in September.

Mulgrew’s comments come a day after thousands of public school teachers staged a series of “teach-ins” intended to draw attention to the ongoing contract talks with the city.

The union said the purpose of the teach-ins — which took place during staff lunch times and did not involve students — was to “brainstorm ways to fight for a fair contract.” Public employees in New York are not legally allowed to strike.

Charles Lutvak, a spokesperson for the mayor, said the administration does not comment on ongoing negotiations.

The labor action underscored the difficult test on unions that the mayor faces. Adams has warned that the city cannot afford to dole out large raises to the city’s roughly 300,000 municipal workers, and has argued that the slow recovery as well as a possible recession could wreak havoc on the city’s budget.

At the same time, he has forged strong relationships with labor unions, including DC37, the city’s largest municipal union, which is currently in negotiations with the administration and is expected to set the bargaining pattern for other non-uniformed unions. Unlike the UFT, DC37 had endorsed Adams for mayor in the primary. The UFT later backed Adams for mayor in the November general election.

Labor leaders like Mulgrew are asking the mayor to recognize the work and sacrifices of their union members during the unprecedented pandemic.

Monday’s teach-ins occurred less than a week after Adams delivered his State of the City address, which was framed as a “working people’s agenda” that included a tribute to city workers for their service.

Some union leaders questioned the mayor’s sincerity.

"While we are encouraged by many of Mayor Adams' efforts to revive New York City's economy, a true recovery can't happen without rebuilding the city's workforce, which has been hammered by budget cuts, a reduced headcount, and an inability to attract candidates or retain employees because of stagnated salaries,” said Harry Nespoli, who chairs the Municipal Labor Committee, an umbrella group representing the city’s unions, in a statement.

Mulgrew described the mayor’s speech as “ironic,” adding, “Thank you for the words. Can we actually see real action on that?”

Adams’ nearly $103 billion preliminary budget plan sets aside enough money in the city’s labor reserve to pay for an annual 1.25% raise for city workers, an amount that experts say will not be nearly enough to reach a deal.

One hurdle to negotiations has been the delay in switching hundreds of thousands of retired city workers to privatized health insurance, a cost-saving strategy that city officials say would save the city $600 million a year.

Despite opposition, which included a lawsuit, the administration appears to be forging ahead with the plan.

During Monday’s teach-in, teachers at Lower Manhattan Arts Academy spoke about how much more difficult their jobs have become during COVID. Students have reported suffering from learning loss as well as anxiety due to the pandemic.

“We intimately deal with the effects of the pandemic with our students who have struggled and continue to struggle,” Julie Roinos said. “That is a whole new level of something we have to deal with on a daily basis.”

Steven Bastias said many teachers worked additional hours during the pandemic to support students and families.

Although inflation has recently shown signs of abating, teachers and other city workers say they have already been forced to bear the spiraling costs in an already expensive city.

“We find ourselves no longer being able to afford the neighborhoods we lived in before,” Bastias said. “We just want to make do, we just want to make ends meet like everyone else.”

Jessica Gould contributed reporting.

Clarification: The story has been updated to specify that the UFT did not endorse Adams during the mayoral primary. The union did endorse Adams during the general election. The story has also been updated to include comment from mayoral spokesperson Charles Lutvak.