TRENTON, N.J. (AP) — New Jersey’s state Senate passed a bill aimed at making it harder for the governor to pull out of an income tax reciprocity agreement with Pennsylvania.

The state Senate voted 39-0 on Monday to require the passage of a law before a governor can end an income tax reciprocity agreement.

The legislation came after former GOP Gov. Chris Christie threatened in 2016 to end the roughly four-decade old agreement between New Jersey and Pennsylvania.

He was seeking cuts in public worker health benefits. But he did not go through with ending the agreement when the Legislature passed a bill to rein in costs.

Terminating the deal could have raised taxes for thousands of New Jersey and Pennsylvania residents who commute across the Delaware River for work.