A deadline to make a deal is 12:01 a.m. Friday.
Negotiations continue as a New Jersey Transit strike looms.
Transit officials met with the engineers union and mediators in Washington D.C. on Monday.
Transit leaders called the discussion constructive.
RELATED: NJ Transit, largest union reach tentative contract deal as engineers' strike looms
The union for the engineers is calling for a higher salary for its members.
A deadline to make a deal is 12:01 a.m. Friday.
NJ Transit has already canceled train and bus service to MetLife Stadium for the Shakira concerts on Thursday and Friday due to the possibility of a strike.