HANOVER, N.H. >> The Dartmouth men’s basketball team voted to unionize today in an unprecedented step toward forming the first labor union for college athletes and another attack on the NCAA’s deteriorating amateur business model.

In an election supervised by the National Labor Relations Board in the school’s Human Resources offices, the players voted 13-2 to join Service Employees International Union Local 560, which already represents some Dartmouth workers. Every player on the roster participated.

The school has five business days to file an objection to the NLRB and could also take the matter to federal court. That could delay negotiations over a collective bargaining agreement until long after the current members of the basketball team have graduated.

Although the NCAA has long maintained that its players are “student-athletes” who were in school primarily to study, college sports has grown into a multibillion-dollar industry that richly rewards the coaches and schools while the players remained unpaid amateurs.

Recent court decisions have chipped away at that framework, with players now allowed to profit off their name, image and likeness and earn a still-limited stipend for living expenses beyond the cost of attendance. Last month’s decision by an NLRB that the Big Green players that they are employees of the school, with the right to form a union, threatens to completely upend the amateur model.

A college athletes union would be unprecedented in American sports. A previous attempt to unionize the Northwestern football team failed because the teams Wildcats play in the Big Ten, which includes public schools that aren’t under the jurisdiction of the NLRB.

That’s why one of the NCAA’s biggest threats isn’t coming in one of the big-money football programs like Alabama or Michigan, which are largely indistinguishable from professional sports teams. Instead, it is the academically oriented Ivy League, where players don’t receive athletic scholarships, teams play in sparsely filled gymnasiums and the games are streamed online instead of broadcast on network TV.

The two Dartmouth juniors at the heart of the union effort, Romeo Myrthil and Cade Haskins, said they would like to form an Ivy League Players Association that would include athletes from other sports on campus and other schools in the conference. They said they understood that change could come too late to benefit them and their current teammates.

Dartmouth has indicated it will ask the full NLRB to review the regional director’s decision. If that fails, the school could take the case to court.

“We have teammates here that we all love and support,” Myrthil said after playing at Harvard last month in the Big Green’s first game after the NLRB official’s ruling. “And whoever comes into the Dartmouth family is part of our family. So, we’ll support them as much as we can.”