Employees at a D.C. charter school are attempting to unionize, a rare move that would make the 115 teachers and staff members the biggest union of charter school workers to ever form in the District.

If successful, Mundo Verde Bilingual Public Charter School would be the only unionized charter campus at the start of the next school year. Teachers at Chavez Prep Middle — a campus that is part of the D.C. Cesar Chavez charter network — are unionized, but that school is expected to close this summer.

Employees at Mundo Verde Bilingual — a top-performing charter school that attracts a lengthy waiting list of students hoping to attend each year — say they want a louder voice in decisions that administrators make. The school in the Truxton Circle neighborhood is expanding and plans to open a second campus this summer.

The employees, who want a pay raise, say they are stretched thin, with too many responsibilities to effectively identify and address students’ needs.

“We are hoping that our voices will be included in the decision-making process in Mundo Verde,” said Amber Walson, a music teacher at the school. “We love our school, we want to collaborate, we want to live the values that our school promotes.”

Charter schools are publicly funded but privately run, and unlike the traditional public school system, their teachers are not usually union members. Nearly 7,000 charter schools serve 3 million students in the country, according to the National Alliance for Public Charter Schools. The American Federation of Teachers says that since 2017, educators at a dozen charter schools nationwide have joined the union. Charter schoolteachers are generally paid less than their peers in traditional public school systems.

In the District, nearly half of the city’s 100,000 public school students attend a charter campus.

When charters were created, one of the objectives of advocates was to free schools from the bureaucratic thicket they say ensnares traditional campuses. Some charter backers view unions as part of that bureaucratic infrastructure.

The efforts to unionize at Mundo Verde had been quietly underway for months, but organizers encountered a hurdle last week when the school administration failed to voluntarily recognize the union by a deadline set by staff members.

School leaders did not reject the union, but in a Friday letter obtained by The Washington Post, administrators requested another meeting with employees this week to better understand what they are seeking.

“We know that every member of the school team seeks to make Mundo Verde the best it can be,” Kristin Scotchmer, executive director of Mundo Verde, wrote in a statement to The Post. “As a result, we need to include all members of our community in this conversation, including those that have reservations about unionization. There is good reason to consider deliberately any implications for Mundo Verde and our school community if a labor contract were to govern how teachers and other staff interacted with administrators, students, and families.”

Federal law says that if administrators do not recognize the union, workers can file a petition with the National Labor Relations Board that could lead to an election involving school employees to decide whether to form the union. Walson said more than 90 staff members — a majority of employees — have said they support the union.

The teacher attrition rate at Mundo Verde was 27.9 percent during the 2017-2018 academic year, according to the school’s annual report.

That rate is higher than other D.C. charter schools with similar demographics, according to a 2018 study from the D.C. State Board of Education.

Some parents have rallied behind the union. Pamphlets about the union drive that were distributed to parents and administrators quote eight parents who support the efforts.

“If we trust these passionate, dedicated people to raise our little humans, surely we can trust them at the decision-making table as leaders and advocates for our children,” one parent, Nyaka Mwanza, said in the pamphlet.

If Mundo Verde teachers and other employees unionize, they would be represented by the American Federation of Teachers, the nation’s second-largest teachers union.

“Like so many other educators at charter schools, those at Mundo Verde want to form a union to have a real impact on the decisions that shape their lives and their students’ lives,” Randi Weingarten, president of the American Federation of Teachers, said in an email.