1:20pm: A first-round pick figures to be shipped to Golden State in the proposed deal, tweets Marcus Thompson II of the Bay Area News Group.
1:13pm: Marc J. Spears of Yahoo! Sports classifies the discussions involving Jefferson and Jackson as "advanced" (Twitter link). TNT's David Aldridge also says an agreement is close, and points out that Spurs coach Gregg Popovich has always liked Jackson (Twitter link).
Neither player has a particularly appealing contract — Jefferson has two years (second-year player option) and $21MM+ remaining on his deal after this season, while Jackson is under contract for $10MM+ next season. The Warriors acquired S-Jax just two days ago from the Bucks.