Just before the fall semester in 2016, the National Labor Relations Board delivered a ruling that emboldened a nascent movement of graduate students at Brandeis University. The board said teaching and research assistants at private universities are employees with the right to form unions.

“There is great feeling on the part of students that they’re not heard by the administration, they’re not valued,” said Benjamin Kreider, a doctoral candidate in public policy at the school in Waltham, Mass. He and others mobilized for collective action, leading to a graduate student vote to join the Service Employees International Union. They are part of a larger movement that has grown since the NLRB ruling last August.

But their efforts could be derailed as a partisan shift on the labor board, from Democrat to Republican, signals that last year’s ruling could be overturned.

Graduate students at approximately 15 private universities across the country have filed petitions or participated in elections to form unions in the last year, said William A. Herbert, the executive director of the National Center for the Study of Collective Bargaining in Higher Education and the Professions at Hunter College in New York. Many grad students say collective bargaining is the only way universities will listen to their demands for balanced workloads, higher pay and comprehensive health insurance.

It is hard to quantify the cost to universities or the benefit to graduate students at these private schools because the campaigns of the last year have yet to produce a contract. Collective bargaining among graduate students is a contentious issue that is as much about economics as it is about power.

“The growing wave of private college organizing has emerged for one core reason — the desire among grad workers to use their freedom to have a real say over the work they do,” said Randi Weingarten, president of the American Federation of Teachers. “The truth is that grads, alongside a growing army of their contingent academic peers, grade the papers, teach the classes and perform the research that creates new knowledge and keeps universities running.”

Graduate students have nevertheless encountered resistance from some universities. Loyola University Chicago and Boston College are challenging the NLRB’s certification of graduate unions on the grounds that the board has no jurisdiction because of the schools’ affiliation with the Catholic Church. In a letter to students and faculty Monday, Boston College Provost David Quigley said the school also joins institutions such as Columbia University and Seattle University in opposing the very premise of the board ruling.

“Our position is that our graduate student research and teaching assistants are best characterized as students — not employees — and that the mentoring relationship to which faculty commit themselves in the scholarly training of graduate students is a partnership that differs from that of university employees or any other workplace association,” he wrote.

That argument could gain traction as Republicans are poised to take control of the labor board. President Trump named Philip A. Miscimarra, who was the only dissenter in the graduate ruling, chairman last spring and nominated lawyers Marvin Kaplan and William Emanuel to fill two of the five seats on the NLRB. Kaplan won Senate confirmation this month, while Emanuel is still waiting for a vote. Once they are installed, many observers expect the board to revisit the ruling.

“Because the chairman of the NLRB wrote a vigorous dissent in the case, one would have to assume that when there is a Republican majority, this is one of the decisions that’s going to be reversed,” said Joseph Ambash, a Boston lawyer who has represented universities in fighting graduate bids to form unions. “The new majority is likely to take up the pending appeals from universities … and those appeals may result in a different outcome than would have been the case under the Obama board.”

The NLRB declined to comment.

There is a history of the labor board shifting positions on the question of graduate workers’ rights that tracks closely with the party in power. The board supported collective bargaining for grad students at New York University in 2000, but four years later, with new members appointed by President George W. Bush, it reversed the ruling in a case involving Brown University. That decision was then overturned in 2016 by a board largely appointed by President Barack Obama.

Teaching and research assistants at Columbia reignited the fight three years ago by filing a petition with the NLRB to join the United Auto Workers. The Massachusetts of Institute of Technology, Stanford University and the entire Ivy League submitted a brief that said bringing students to the table would disrupt operations if negotiations included the length of a class, amount of grading or what’s included in curriculum.

Michael Burrows, a doctoral candidate and research assistant at Duke University, said the contributions of graduate students as instructors and researchers should afford them the same basic rights as any other employee at a university. He said that after Trump’s election, union organizers at Duke sped up their campaign to join the SEIU out of concern that the new administration would overturn the Columbia ruling.

The results of the vote in February were indeterminate after the university challenged the eligibility of more than 500 ballots, but a preliminary tally was decidedly against unionization. Rashmi Joglekar, president of the Graduate & Professional Student Council at Duke, said students may not have “clearly understood the benefits or detriments” of being part of a union, and the campaign became very polarized.

Burrows said the university undermined the campaign by stripping voting rights from students who were not teaching during the semester and took a combative stance from the beginning. Duke spokesman Michael Schoenfeld called that perspective an “inaccurate assessment that doesn’t recognize the collaborative relationship that exists between graduate students and the university.” He said Duke just announced that it would be providing scholarships for all sixth-year graduate students, an issue that the graduate student council advocated.

Although the university will not recognize the graduate union, Duke students have affiliated with the SEIU.

“We want Duke to bargain with us … but dealing with the hand we’ve been dealt, this seems like the best-case scenario,” Burrows said. “We want to see teaching done better, research done better, so we’re trying to draw attention to that and oppose the increasingly corporate structure that we see at private universities.”

Herbert, at Hunter College, said there has been a divide among universities in how to engage graduate unions. While some schools have vehemently opposed student bargaining, others such as Brandeis, Tufts University and American University have let the process proceed with little objection.

Brandeis Provost Lisa Lynch said the university “looks forward to working with the SEIU to reach a collective bargaining agreement with PhD students who teach, and recognize them as vitally important members of our community.”

With the threat of a reversal of the NLRB ruling under Trump, universities could play an outsize role in the future of graduate worker rights. When the labor board overturned the NYU ruling, for instance, the university still chose to recognize its graduate student union.

“We hope that universities, as progressive institutions which have already taken legal actions against the administration, would bargain with us in good faith regardless of who Trump appoints,” Kreider said. “Student workers remain committed to organizing for improvements no matter what happens.”