Marathon Petroleum (MPC) and the United Steelworkers will continue bargaining for a national agreement covering workers represented through the USW National Oil Bargaining Program past contract expiration, the union said Saturday.

The program includes more than 30,000 oil workers across various employers in more than 200 bargaining units, according to the USW.

The extension means that the current contract will remain effective until either the union gives a 24-hour notice to strike or Marathon issues a 24-hour notice to lock workers out, Reuters reported. The union has rejected at least five proposals from the company since the start of negotiations, according to the report.

"[Marathon] continues to meet with representatives from the USW," the news agency reported, citing a company spokesperson. "We are committed to bargaining in good faith and to working toward a mutually satisfactory agreement."