The US United Auto Workers union qualified for partial recognition at the Volkswagen plant in Tennessee on Monday.
The deal gave the union its first formal role in a foreign-owned car plant in the southern US.
An independent auditor verified that UAW Local 42 had signed up at least 45 per cent of workers at the Chattanooga plant.
While the new status doesn’t include collective bargaining, UAW secretary-treasurer Gary Casteel hailed it as a “starting point” at the plant.
The UAW narrowly lost a trade union recognition vote at the plant in February after a smear campaign by local Republican politicians claimed that state incentives needed to expand the plant would be threatened if the union won.
Workers who spearheaded the 712-626 defeat in February have created their own organisation called the American Council of Employees but have failed to qualify for recognition under the new policy.