After years of legal wrangling that spanned two presidential administrations, organizers successfully argued that the group of 75 tool and die technicians are eligible for standalone representation because they have extremely specialized skills for a job that can’t be done by others at the facility. The Japan-based company has contended the employees are not sufficiently distinct from other plant workers to be eligible for their own unionized bloc.

Organizers have cited a variety of reasons to unionize at the Nissan plant in Smyrna, about 25 miles (40 kilometers) outside Nashville. Those include retirement, work-life balance and health care issues they want to negotiate.

Nationwide, several high-profile unionization campaigns — at Starbucks, Amazon, Apple and other companies — have given organized labor a renewed spotlight of late, even as the union membership rate reached an all-time low last year. The number of workers belonging to a union actually increased by 1.9% to 14.3 million, but that failed to keep pace with higher overall employment rates.

A federal ruling in 2021 nearly killed the union drive in Smyrna. After that decision was overturned this year, organizers said the election could now be a close call instead of an easy win, saying years of waiting have taken a toll on the campaign.

A National Labor Relations Board official sided with Nissan in June 2021, ruling that the smaller group of workers couldn’t vote to unionize without including thousands more employees at the plant. The union didn’t pursue the facility-wide vote.

But once the U.S. Senate completed its confirmations of new Biden administration appointees, control of the board switched from Republicans to Democrats. The panel overturned the previous ruling last month, giving the union a green light for the vote.

Since plant workers first reached out to the machinists union in 2020, some supporters have quit, others retired and some moved on to unionized workplaces elsewhere, said Tim Wright, grand lodge representative for southern territory with the International Association of Machinists and Aerospace Workers.

“This two-year process, it chilled this campaign to the point to where this is going to be a close election, potentially,” Wright said in an interview Tuesday. He said he hopes the campaign can create a “buzz” with other workers as well.

A spokesperson for Nissan, which has about 7,000 employees at the Smyrna facility, has said the company believes its workplace is “stronger without the involvement of third-party unions” like the machinists union. Still, it emphasized that employees have the right to decide whether to join a union — a right that has been enshrined in federal law since the 1930s.

Unions have run into opposition from Republican politicians when they attempt to organize at foreign automakers in the South, including in Tennessee. Still, it doesn’t appear that GOP officials have sought to weigh in much on the campaign at Nissan.

Tennessee already has a big union presence at an American automaker: The General Motors plant in Spring Hill has thousands of production and skilled trades workers represented by the United Auto Workers union.

In a radio ad for the campaign — which featured former University of Tennessee and Pittsburgh Steelers football player Ramon Foster — the machinists union highlighted its representation of some workers at Trane Company, Tennessee Valley Authority, Arnold Air Force Base, Oak Ridge National Laboratory, NWI Aero and in the railroad industry.

Nissan does work with organized labor in the rest of the world, but votes to unionize broadly at the two Nissan plants in the U.S. have not been close. Workers in Smyrna rejected a plantwide union under the UAW in 2001 and 1989.

The automaker’s other U.S. assembly plant in Canton, Mississippi, rejected facility-wide representation by the UAW during a 2017 vote.

The margin was much closer in 2014 and 2019 votes at the Volkswagen plant in Chattanooga, Tennessee, where workers twice rejected a factory-wide union under the UAW.

The year after the 2014 vote failed, 160 Chattanooga maintenance workers won a vote to form a smaller union, but Volkswagen refused to bargain. The German automaker had argued the bargaining unit also needed to include production workers. As a result, the 2019 factory-wide vote followed.

There’s also an open question about whether workers will unionize at four sprawling new factories planned by Ford in Kentucky and Tennessee by 2025, with an aim of hiring nearly 11,000 workers. Three of the plants — two in Kentucky, one in Tennessee — will be built with Ford’s South Korean corporate partner, SK Innovation, to produce electric vehicle batteries. A fourth, in Tennessee, will make electric F-Series pickup trucks.