When the PGA Tour and the upstart LIV Golf league, which is bankrolled by Saudi Arabia’s sovereign wealth fund, announced their groundbreaking deal in June for the men’s golf circuits to join forces, they left most details unanswered and set a Dec. 31 deadline to figure them out.

Now, it is clear that the two sides will need more time.

The PGA Tour commissioner, Jay Monahan, said in a memo to players Sunday evening that the PGA Tour and Saudi Arabia’s sovereign wealth fund, the Public Investment Fund, were “working to extend” the negotiations into the new year.

The sides had been discussing signing a formal one-month extension, which could be further prolonged, said three people familiar with the negotiations who were not authorized to discuss them. But while both sides remain focused on completing a deal, they have yet to set any new formal deadline.

Those negotiations continue as the PGA Tour progresses on simultaneous talks to raise additional money from Strategic Sports Group, an investment group led by Fenway Sports Group — the parent company of the Boston Red Sox, the Pittsburgh Penguins and the English soccer club Liverpool.

Mr. Monahan said on Sunday that the tour and Strategic Sports Group “have made meaningful progress” in their talks and that the tour had “provided S.S.G. with the due diligence information they requested.” The parties are focused on finalizing terms of the deal and documents, he said.

The PGA Tour, the Saudi wealth fund and the Strategic Sports Group enter 2024 with significant uncertainty about the deal. Since the June announcement, questions that had initially accompanied the agreement’s frenzied rollout appear to have compounded: How will potential U.S. investment sit alongside Saudi money? How will the golf circuits work together even as the Saudis still actively seek to poach PGA Tour players?