After months of optimism surrounding a potential new collective bargaining agreement that would allow the NBA and the players’ union to avoid another work stoppage, the momentum has slowed a bit as a critical date approaches.

Both sides have until 11:59 p.m. on Thursday to opt out of the current deal. If that were to happen, they would have until the end of June to negotiate a new contract. Neither the owners nor the players believe it will get to that point, with both sides seeking a deal to ensure the league keeps enjoying skyrocketing revenue and rising television ratings.

“We’re working tirelessly,” union president Chris Paul said this weekend.

Many of the major parts of the deal have been addressed, including keeping the basketball-related income split the same as it is in the current agreement. There was a belief in early November that an accord could be struck by Thanksgiving, but the complex negotiations have carried on well into December.

There remain a few issues for the sides to settle before a deal can be voted on, and the owners overseeing the league’s side of the negotiations planned to meet on Monday for a progress report. If the two sides do not agree to a deal by the deadline, they could implement an extension to give them extra time.

While union vice president Carmelo Anthony told ESPN that he was “skeptical” that a deal would get done by Thursday, there remained a healthy amount of optimism from both sides of the negotiating table that a deal will eventually be reached.