More than 37,000 Verizon employees have remained on the job despite their contracts’ expiring at midnight Saturday, the Wall Street Journal reported. Located in nine states from Massachusetts to Virginia, the employees are members of Verizon’s two largest unions, the Communications Workers of America (CWA) and the International Brotherhood of Electrical Workers, and include technicians and call center staff supporting Verizon’s landline business.

At least one of the unions, the CWA, has already received authorization from its members to strike (86% of members approved the authorization). However, the Wall Street Journal notes that Verizon has been training thousands of nonunion workers to replace union members, in the event that a strike is called.

After six weeks of intense negotiations, union representatives walked away from the bargaining table. Verizon was seeking an agreement which entailed reducing retirement benefits and shifting more healthcare costs onto employees. The unions’ proposals included provisions securing greater employee benefits and job security for its members. The CWA also expressed concern that some of Verizon’s proposals could eliminate thousands of jobs through subcontracting and outsourcing, and could also result in forced job transfers.

Each side had bitter words for the other.

“[The unions] know firsthand that our [landline] unit is facing significant challenges. Unfortunately the union leadership doesn’t want to recognize the facts and decided that walking away was the best course for its members,” said Verizon spokesman Rich Young.

“Verizon is making the same demands it made six weeks ago, and that’s not a negotiation,” said Candice Johnson, a CWA spokeswoman.