The NFL and the NFL Players Association are reportedly unlikely to find common ground on the league's national anthem policy before the regular season kicks off Sept. 6. 

According to ESPN.com's Dan Graziano, the sides have had constructive dialogue since a freeze was placed on the new anthem policy that owners unanimously approved in May, and there is "optimism" a resolution will eventually be reached. 

However, Graziano spoke to sources who said "each side is curious to see how the other handles issues that arise moving forward, such as whether players will continue protesting during the anthem, what owners and/or the league will do, and if President Donald Trump continues to mention it."

On Monday, the NFL and NFLPA issued a joint statement regarding the ongoing discussions. The talks were classified as "productive," although details remained elusive. 

The new policy passed in May would require players and team personnel on the sideline to stand for the national anthem. Players have also been given the option to stay in the locker room. 

Under that policy, players who choose to kneel or sit during the anthem would be subject to fines.