Faculty at Rutgers University this week took a step that could bring their union closer to calling the first strike in the school’s 253-year history, the union announced Tuesday.

“We do not want to have to call a strike unless we absolutely have to,” said Deepa Kumar, president of the union, which represents 4,800 full-time faculty and graduate students on Rutgers’ New Brunswick, Camden, and Newark campuses. “We are fighting to defend quality public higher education, and this is not just about the faculty and graduate students. This is about our students.”

Faculty voted to authorize the negotiating team to call a strike if necessary. It’s a tactic that’s typically employed by unions when negotiations drag, though Kumar said Rutgers faculty haven’t had to use it for at least the last two decades. The voting took place over the last week, with 88 percent endorsing the measure, Kumar said.

The union and faculty have been negotiating for about a year; their last contract expired in June. The latest move follows pickets, protests, and other actions by faculty, who have expressed increasing frustration with university leadership.

The university administration said in a statement that it had met with faculty union leadership 33 times and has two more sessions scheduled through the end of March.

“The parties are making progress, and the university continues to negotiate in good faith,” said spokesperson Dory Devlin.

She added that the university has reached agreement with six other unions and tentative agreement with a staff union, collectively representing about 25 percent of the unionized workforce. Contracts reached generally have provided employees with 3 percent raises in each of the next three years and a 2.5 percent increase in the final year, she said.

Main issues of contention in faculty negotiations center around equitable pay and larger class sizes. Faculty, Kumar said, are worried about an increase in the full-time faculty-to-student ratio. In 1998, Rutgers employed 2,123 full-time tenure-track faculty and enrolled 35,705 undergraduates, she said. Today, the number of faculty has barely changed, but the student body has grown to 49,861, she said.

“Rutgers has hired an army of underpaid part-time lecturers, close to 3,000 of them,” Kumar said.

Fewer full-time faculty means less focus on research, part of Rutgers’ primary mission, she said.

Concerns also have mounted around equable pay for female faculty, she said.

“We believe that women faculty who do the same work as male faculty should earn the same salary,” said Kumar, a professor of media studies based in New Brunswick.

Average professor salaries at the New Brunswick campus in 2017 ranged from $61,799 for a lecturer to $148,347 for a full professor, according to the Chronicle of Higher Education.

Faculty have taken aim at Rutgers president Robert Barchi, who has led the school since 2012 and recently got a two-year contract extension to 2020.

“We are particularly alarmed at the spending priorities of the Barchi administration," said a faculty petition signed by a group of full-time professors, posted this month.

They cited 244 Rutgers administrators who earn more than $250,000 and “golden parachutes” — settlements and buyouts — totaling $11.5 million for administrators and coaches. They also cite the spending of academic dollars on an athletic program that has consistently run in the red, rising tuition costs, and lack of fair wages for student workers and adjunct faculty.

Graduate students, Kumar said, haven’t received a raise in five years and are paid $26,000. Any raise given will be distributed in dollars rather than a percentage so that lower-paid employees benefit, she said.

Lack of adequate faculty diversity also has raised concern, she said. Only about 9 percent of full-time faculty are African American and Latino/Latina, she said.

The administration declined to discuss issues of contention in the negotiations.

Kumar said the union isn’t prepared to let talks drag on a lot longer.

“If we don’t see serious progress in the next few weeks, then the strike option would be something we would look to use, to be taken seriously," she said.