The parent company to YRC Freight and others, YRC Worldwide, announced it was ending a contract extension with the International Association of Machinists as of Monday. 

In a release, the company said it will continue to talk with the IAM, though it points out the lack of significant progress in the negotiations led to the lock-out. The company is reportedly hopeful the situation will be resolved.

Of the company's 32,000 employees, YRC Worldwide says less than one-tenth of 1% is represented by the IAM. 

YRC says it has contingency plans in place to ensure there is no interruption of its operations or disruptions in customer service.

The contract with IAM employees originally was scheduled to expire on March 31. Negotiations continued during a mutually agreed-upon extension of the contract. 

YRC says “IAM has refused to accept the same shared-sacrifice measures that all other union and non-union employees of YRC Worldwide have accepted.”

IAM is not affiliated with the Teamsters Union, which has agreed to a series of wage and benefit cuts to help the financially struggling operation.