The NFL owners have approached the NFL Players Association several times over the past few months about an extension of the current collective bargaining agreement.

One reason the owners want an extension is because they have exhausted all of the stadium credits that were negotiated in the 10-year deal with the players that was signed in 2011. 

The NFL would like to secure money to help fund a stadium in Las Vegas for the Raiders and possibly another in San Diego.

The NFLPA would listen to the league's overtures, but it's likely the players would require somewhat significant concessions from the owners to agree to an extension at this point.