Teaching and research assistants at Harvard University went on strike Tuesday after more than a year of trying to negotiate their first contract with the Ivy League school.

Members of the Harvard Graduate Students Union-United Automobile Workers began picketing on campus Tuesday morning to protest what they say are inadequate wages, health-care benefits and protections against harassment and discrimination. Graduate student workers say they will not administer exams, grade papers or complete research until their demands are taken seriously by the university.

“We’re sick of not getting responsive proposals from the administration,” said Lee Kennedy-Shaffer, a doctoral candidate in biostatistics at Harvard and union negotiator. “We set this strike deadline a month ago, and since then we’ve had barely any bargaining time with the administration.”

The strike arrives as the university, which relies on graduate students to teach and perform research, is wrapping up the semester. Harvard has been developing contingency plans since the union announced a vote on the strike six weeks ago and says it expects limited disruption.

Negotiations began in earnest in October 2018, six months after graduate student workers voted to form the bargaining unit. Twenty-eight negotiating sessions have been held, and more than 40 proposals have been issued, with the parties reaching tentative agreements on 12 of those plans, according to the university.

“Student workers have a vital role in fulfilling Harvard’s teaching and research mission, and with that in mind, the University is committed to addressing concerns that have been raised throughout this process,” according to a statement issued Tuesday by Harvard. “A strike will neither clarify our respective positions nor will it resolve areas of disagreement.”

Chief among the points of contention in contract negotiations are calls for comprehensive mental-health care, expanded tuition benefits and revisions to the sexual harassment policy.

This year, the graduate student union ran advertisements on cable television, social media and radio demanding Harvard enact new harassment and discrimination protections for teaching and research assistants. Student workers want an independent grievance process for survivors of harassment guaranteed through a union contract, arguing that the only way to change the culture and balance of power at Harvard is through a process arbitrated by independent parties, not employees of the university.

“Every time we provide a proposal that tries to seek a framework that both sides can agree on and meets the needs of our members, [the university] responds by barely moving the proposals,” said Kennedy-Shaffer, who is a teaching assistant.

Harvard administrators argue the university has offered proposals that are responsive to concerns raised by the union, including increased compensation and benefits. But the university is reluctant to acquiesce to several of the union demands involving financial aid and harassment policy. Harvard administrators say the union arbitration proposal could undermine and further complicate the procedures in place.

Harvard was among many universities that fought graduate unions on the grounds that students are not employees, even after the National Labor Relations Board granted teaching and research assistants at private schools legal protections to unionize in 2016.

In the past year, graduate unions at Brandeis, Tufts and American universities and the New School have ratified their first contracts, according to Hunter College’s National Center for the Study of Collective Bargaining in Higher Education and the Professions. But gains made in the graduate student labor movement could be undermined by the labor board’s recent reversal on its 2016 decision.

In September, the labor board issued a proposed regulation asserting that graduate workers are students above all else, not employees of their universities, even if they assist in teaching courses and research that benefits schools. While the legal protection of the board is important, graduate students can collectively bargain without those protections if the university is willing to come to the table.

Harvard administrators said “the university is currently reviewing the [labor board’s] proposed rule to assess its implications on the ongoing negotiations. In the meantime, negotiations are continuing and bargaining sessions are already on the calendar for the weeks ahead.”