UAW Secretary-Treasurer Gary Casteel has confirmed that the organization has been in contact with employees at Tesla’s plant, operating in a supportive capacity to gauge interest in unionizing the operation.

Located in Fremont, California, the 5.3 million square foot Tesla plant currently employs 6,000 workers and is the only American-owned facility based in the U.S. that is not unionized. The Tesla plant was formerly owned by New United Motor Manufacturing Inc., a joint venture between General Motors and Toyota. The NUMMI plant operated under union representation between 1984 and 2010.

While the UAW has maintained an active interest in the plant, union President Dennis Williams told the media in May that it has not assigned organizing staff to the Tesla facility while the company remains in startup mode.

Tesla CEO Elon Musk recently indicated that the company will ramp up annual output at the plant to 500,000 vehicles by 2018, a move that will make it more of a target for unionization.