NEW YORK (AP) — Graduate teaching assistants at private universities had high hopes 18 months ago when a federal labor board ruled that they had a right to collective bargaining, but after the election of President Donald Trump, some schools are taking another shot at halting the burgeoning unionization movement.

Columbia University announced in a university-wide email Tuesday that the school wouldn't bargain with the graduate students who voted more than 2 to 1 for union representation, and would instead appeal to a federal court. Yale and Boston College, among others, have also filed legal appeals, rather than begin negotiating with newly unionized students.

It may be a sign that administrators are anticipating that the National Labor Relations Board, now being reconstituted with appointees of the strongly pro-business Republican president, will reverse the decision it made in 2016 and declare that graduate students are not employees after all.

"It's not a crazy strategy to stall because it is very likely that this board with a number of appointees from Trump will return to the idea that graduate students are primarily students," said Harry Katz, a professor of collective bargaining at Cornell University's School of Industrial and Labor Relations.

Unions have represented teaching and research assistants at public universities for decades, but New York University is the only private university in the U.S. with a collective bargaining agreement with graduate students.

Universities have generally argued that even though graduate teaching assistants are paid — their mean annual pay was $35,810 in 2016, according to the Bureau of Labor Statistics — treating them like employees would disrupt the mentoring relationship between budding scholars and the professors supervising their academic pursuits and research.

The NLRB's position on whether students have a right to unionize has shifted.

In 2004, during the presidency of George W. Bush, a Republican, the board ruled that graduate student instructors are not employees. The board reversed itself in 2016 under President Barack Obama, a Democrat.

The five-member NLRB currently has four members who are split evenly between appointees of Trump and Obama. Trump's nominee for the fifth seat, management-side labor lawyer John Ring, awaits Senate confirmation.

Chaz Lee, a graduate student in music history at the University of Chicago, said a pro-union vote there in October was "a really heartening moment for all of us."

He had hoped it would lead to better pay and health insurance coverage. Many graduate students struggle to find affordable housing near the university, he said.

"Some departments give raises; some don't," he said. "None of these are enshrined in a contract that ensures that our compensation would go up to stay in line with the cost of living."

After the unionization vote, the university filed a motion urging the NLRB to reverse its 2016 ruling and once again designate graduate students as students, not workers.

"Our concern here is simply about the potential effects of unionization on our ability to provide our students with the individualized support they need to flourish in their research and teaching," University of Chicago Executive Vice Provost David Nirenberg said in a letter to graduate students.

Columbia administrators voiced a similar concern after teaching assistants voted to join the United Auto Workers.

"We remain convinced that the relationship of graduate students to the faculty that instruct them must not be reduced to ordinary terms of employment," Columbia University Provost John Coatsworth said in his email to the university community Tuesday.

Julie Kushner, the regional head of the UAW, said the union hopes to mobilize community opposition to Columbia's decision not to bargain.

"People expect that from a Walmart," Kushner said. "They don't expect it from a prestigious university."

Randi Weingarten, head of the American Federation of Teachers, which is working with graduate students at the University of Chicago and elsewhere, accused administrators of "trying to run out the clock," on the unionization movement, "cynically calculating that a Donald Trump-appointed board will move to trample it."

Some universities have not said outright that they won't bargain with graduate students but have filed appeals challenging the validity of elections.

Boston College has argued that the NLRB rulings don't apply because it is a Roman Catholic institution.

Other universities, including American University in Washington, D.C., and Tufts and Brandeis in the Boston area, have agreed to negotiate with newly unionized students.

Stephan Lefebvre, a graduate student in economics who is on the bargaining committee at American University, said talks are going well.

"I won't be happy until it's in the books," he said.

Matt Dauphin, the higher education coordinator for Service Employees International Union Local 509, which represents grad students at Tufts and Brandeis, said negotiations started last fall at both campuses.

"At this point we are optimistic about our chances to meet a signed contract," he said.

Dauphin said he hopes the negotiations will continue even if the NLRB reverses itself on graduate student union rights.

"We're hopeful that no matter what decision might come down the pipeline, these employers will continue to do the right thing," he said.

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