(Reuters) - Phillips 66 and labor leaders representing workers at its 285,000 barrel per day Bayway refinery in Linden, New Jersey, will resume negotiations next week, according to a source familiar with the talks.

However, union workers at the Teamsters Local 877 said they were “preparing for the worst” whether it is a strike or a lockout, and that a date to resume conversations has not yet been decided.

The two sides hit an impasse late last week after failing to agree on changes to the contract expanding the tasks and responsibilities of refinery workers, which some union members deem a safety issue.

A three-year contract was voted down by union members earlier this month, and operations have continued under a 24-hour rolling contract that has been in place since the previous contract expired.

Phillips 66 did not immediately respond to a request for comment.

The Bayway refinery is the largest in operation in the U.S. Northeast following a fire and series of explosions in June that led to the closure of the 335,000-bpd Philadelphia Energy Solutions facility.

Refining capacity in the region has declined over the years as much of the nation’s refining output now comes out of the U.S. Gulf Coast and Midwest.

The union represents about 500 operators at the Bayway facility, which employs around 800 people, according to the company’s website.

If an agreement is not reached, the unionized refinery workers could be subject to a lockout, leaving the company without access to certain union-trained workers who handle emergency response systems.

However, Phillips 66 said in a previous statement that they “maintain qualified emergency response personnel who are not represented by the Teamsters Local 877.”