For many years, Chicago has served as a pivotal location for the Democratic Party’s significant shift in education policy.

With the backing of longtime resident Barack Obama, then President, and his close ally Rahm Emanuel, who was the mayor at the time, the city moved away from policies endorsed by teachers’ unions. Instead, it embraced initiatives aimed at giving families more options and ensuring accountability, such as charter schools and grading systems that evaluated schools based on student test scores.

That was the past.

Today, Chicago is engaged in a dramatically different experiment: exploring the outcomes of a powerful teachers’ union successfully supporting the election of a mayor who largely adopts the union’s agenda.

On one side, the results have been positive. The district’s 300,000 students have shown impressive recovery from learning losses incurred during the pandemic, and a record number are enrolling in college-level courses.

Conversely, the city is facing significant financial and political challenges. The school district utilized federal Covid-19 relief funds to employ thousands of teachers, coaches, counselors, nurses, and social workers, all while student enrollment was declining.

As these funds dwindle, the district now faces a budget shortfall of hundreds of millions of dollars. Mayor Brandon Johnson, a former social studies teacher and union organizer, has attempted to remove the chief executive of schools, Pedro Martinez, who has resisted the mayor’s suggestion to secure a high-interest loan to bridge the financial gap.

In the midst of this conflict, the entire school board resigned this month and has been replaced by new members appointed by the mayor.

The political landscape may shift again soon. On Election Day, voters will have their first opportunity in decades to elect 10 school board members, following years of advocacy by the Chicago Teachers Union to end mayoral control and restore elections.

“The Chicago Teachers Union has effectively become a powerful political force in the city,” noted Paul Vallas, a former school superintendent and critic of the union, who ran against Mr. Johnson in the mayoral race last year.

Critics of the mayor argue that he should assert himself against the union by closing under-enrolled schools, downsizing staff, and rejecting the union’s request for a 9 percent salary increase.

However, Mr. Johnson believes he has little reason to oppose the union’s agenda, as he sees it as aligned with his vision. He has highlighted that children in Chicago’s low-income areas have historically lacked equal access to libraries, arts programs, athletics, advanced academics, and quality vocational training.

He argues that previous adversarial relationships between mayors and union leaders have resulted in poor outcomes for Black and Hispanic students and have diminished Black teaching jobs.

“What will we commit to support?” Mr. Johnson asked in an interview. “I was elected to invest in people. That’s exactly what I’m doing.”

As a former educator who strongly supports union-friendly education policies, Mr. Johnson represents a growing faction of Democrats, including the party’s vice-presidential candidate, Minnesota Gov. Tim Walz.

Their visibility is particularly striking given that the unions’ backing of prolonged pandemic-related school closures sparked considerable discord among progressives nationwide.

However, this debate has diminished in importance since schools reopened. In major cities like Chicago, New York, and Los Angeles, a pressing issue now is sustaining services as student enrollment declines, given that school funding is allocated per pupil.

Over the past decade, families have departed urban school systems for numerous reasons, such as high housing costs, dissatisfaction with virtual learning during the pandemic, and the appeal of charter and private schools.

While enrollment in Chicago and other cities has increased slightly over the past two years, numbers remain significantly below pre-pandemic levels.

Yet, Mr. Johnson and his ally, Stacy Davis Gates, president of the Chicago Teachers Union and also a former social studies teacher, believe that fewer students shouldn’t equate to fewer schools.

They cite research indicating that when Mr. Emanuel closed 50 schools in 2013, the financial benefits were minimal, and students from those schools suffered academic setbacks in the years that followed.

Instead, Mr. Johnson and Ms. Davis Gates advocate for increased investment in schools that currently have low attendance. For instance, Frederick Douglass Academy High School on the West Side once had over 500 students enrolled in 2007 but now serves only 34.

The two emphasize a transformative agenda for Black and Latino students, framing their goals in historical terms.

“The initial purpose of Chicago Public Schools was twofold: to uphold segregation and to provide the working class with access to jobs in the stockyards and factories,” Ms. Davis Gates stated.

In her view, 2024 calls for a fundamental reevaluation of the education system’s purpose, which should be to ensure every Chicago student has access to a high-quality local school enriched with bilingual programs, extracurricular activities, and the arts.

She described the mayor as justifiably “impatient and intolerant of prolonged delays.”

The two share a personal friendship, and both have mentioned that their commitment to maintaining neighborhood schools is influenced by their experiences as Black parents in historically marginalized communities.

Mr. Johnson’s eldest son attends a magnet school in a different area, attracted by its orchestra and Advanced Placement offerings. Meanwhile, Ms. Davis Gates noted that one of her three children enrolled in a private school due to its superior athletics.

Mr. Martinez, the chief executive of schools, also has children in the district. He agrees with the aim of developing new programs to attract students back to under-enrolled schools and noted that Black students often travel the farthest across the city to find preferred schools.

However, Mr. Martinez expressed that his primary disagreement with the mayor lies in their funding strategies. While Mr. Johnson has suggested that no funding avenue should be overlooked, Mr. Martinez argues that taking out a loan would simply recreate past mistakes and leave the district burdened with debt. He advocates for utilizing property tax surpluses and seeking increased state and federal funding instead.

Andrew Broy, president of the Illinois Network of Charter Schools, contended that instead of pouring funds into struggling, low-enrollment schools, Chicago’s education leaders should implement policies that empower parents to choose quality schools that meet their needs.

He argued that the interests of students and taxpayers are often overlooked when the mayor and the teachers’ union president are closely aligned in negotiations.

“When both parties are on the same side, the ones left out are students and taxpayers,” he explained. “Without their input, they end up being neglected.”

In the late 1990s and early 2000s, Chicago, along with several other cities, shifted from elected school boards to mayoral control, part of a broader national effort to enhance accountability in public education. However, the academic and political outcomes of this shift were mixed. In 2021, Illinois Gov. JB Pritzker, a Democrat, signed legislation reinstating an elected school board in Chicago. As the first vote to elect new board members approaches on Election Day, both the union and its critics in the charter-school community are investing significant resources in direct mail campaigns.

Union supporters have accused their Democratic opponents of adopting a Trump-like agenda, while charter advocates are challenging Mr. Johnson’s commitment to prioritize traditional neighborhood schools over charters, magnet schools, and selective enrollment options.

The union views the elected board as an opportunity to influence educational governance, but the shift to elections also presents a chance for opponents to gain seats.

Even some members of the left-leaning Chicago City Council have begun to question the mayor’s budgetary approach, expressing concerns about accruing additional debt amid existing pension obligations.

Andre Vasquez, a City Council member, pointed out that he, like the mayor, entered office with a history of progressive activism. However, he argued that the responsibilities of these roles are fundamentally different.

“Many of us are accustomed to protesting,” he said. “Now, the focus is on delivering results, which is a much more nuanced challenge.”