Nissan Motor Company’s resistance to attempts by United Auto Workers (UAW) to organize the workers at its Smyrna, Mississippi plant continues, even as the union formally requested a State Department mediator be assigned to the situation, claiming that Nissan has been attempting to intimidate employees who are attempting to for a chapter of the UAW at the assembly plant.

However, the mediation can only take place if both sides agree, and Nissan has rejected the proposal, saying the Japanese company prefers to let the existing laws guide the resolution of the union question. It pointed out the existence of guidelines for bringing a union vote, and denied it was making any special efforts to discourage such a vote.

The UAW, for its part, acknowledged that it intended to hold such a vote by the end of 2015. This is not the first time workers at the Smyrna have attempted to organize into a union, with failed attempts in 1989 and 2001; the most recent previous attempt was in 2013. Nissan has generally responded to such attempts with raises and other increased benefits.

The UAW has long targeted the 6,000 Nissan employees in the United States. Most of Nissan’s non-American locations are unionized. The UAW suggests this shows that Nissan treats its U.S. workers differently.

The State Department supported the mediation request, stating that the issues raised by the UAW were material and substantiated. The State Department in turn recommended that Nissan conduct an audit of labor rights in its facilities and that it pursue mediation on its own with workers.