There was no deal on Monday between Major League Baseball and the MLB Players Association for a new collective bargaining agreement, but following a marathon negotiating session that went into the early hours Tuesday morning, there is optimism that the two sides could be nearing an agreement that would allow the regular season to start on time.

Despite MLB’s Monday night deadline to reach a deal before rescheduling Opening Day, the bargaining session -- which lasted more than 16 hours -- prompted the league to move the deadline to 5 p.m. ET on Tuesday. The two sides met again on Tuesday in an effort to work out the details on a new CBA and potentially pave the way for Spring Training camps to open later this week, and for Opening Day to take place on March 31 as scheduled.

• More CBA updates and information

“We want to exhaust every possibility to get a deal done,” a league spokesperson said.

Some progress was made throughout the day on a number of issues, including minimum salary, a pre-arbitration bonus pool and the competitive balance tax, though final details are still being worked out.

One of the biggest issues of the day revolved around an expanded postseason; the league has been aiming for a 14-team field, while the players were countering with a 12-team playoff.

• FAQ on the CBA negotiations

After several bargaining sessions, MLB proposed two separate offers, one with a 14-team postseason that included higher minimum salaries and more money in the pre-arbitration bonus pool, the other with a 12-team field and less money on both other items.

The two sides began the day at 10 a.m., with the first face-to-face meeting taking place approximately one hour later.

That led to over 16 hours of negotiations that included more than a dozen separate meetings, with MLB officials repeatedly making the walk across Roger Dean Stadium to sit down with MLBPA representatives.

At 6:15 p.m., Commissioner Rob Manfred walked by reporters on his way back to the owners’ side, telling the group, “We’re working at it.”

Several meetings followed, as MLB officials including deputy commissioner (and MLB’s lead negotiator) Dan Halem made repeated trips to the players’ side to negotiate.

These sessions progressed into the night, as the sides tried to narrow the gap with the clock ticking toward midnight. That deadline came and went, but MLB and the MLBPA continued to negotiate, believing enough progress had been made to continue working towards an agreement.

Shortly after 1 a.m., Halem and three other MLB officials trekked back to the players’ side for another session.

Two meetings and less than 90 minutes later, the negotiations were finished for the night, as the parties agreed to reconvene late Tuesday morning with the hope of crossing the finish line.