EDISON - New Jersey Transit says that the agency has entered strike preparation mode after its rail unions ignored a request to extend its cooling off period.

The current deadline ends next Thursday. Nine other unions have ratified an agreement reached in March that avoided a systemwide strike.

The National Mediation Board, which oversees the negotiations between NJ Transit and the two remaining rail unions, requested that both parties extend their no strike-no lockout pledge until Congress returns from its recess.

New Jersey Transit agreed, but union leaders did not respond.

This could mean that workers could strike in about three weeks.

Stephen Burkert, general chairman of the conductors' union, posted on the union's website Wednesday that he hadn't agreed to the extension

NJ Transit spokesman Nancy Snyder said in Friday's email the agency and unions have been in contact "many times" over the last few days.

A tentative contract agreement was reached in March. It included retroactive pay, a cap on employee’s health insurance costs and a 21 percent salary increase over three years.

The unions involved are the Locomotive Engineers, Assistant Engineers and Engineer Trainees.

The Associated Press wire services contributed to this report.