The Cleveland Cavaliers remain seriously interested in trading for Chicago's Jimmy Butler or Indiana's Paul George but have encountered significant obstacles on both fronts, according to league sources.

Sources said Tuesday that the Cavaliers have been notified that Butler hopes to stay with the Bulls and would be reluctant to commit his long-term future to Cleveland. Butler, sources said, remains intent on trying to lead the Bulls back to Eastern Conference prominence.

When it comes to George, meanwhile, ESPN reported earlier Tuesday that the Pacers have begun trade talks with the Los Angeles Lakers, who overwhelmingly rank as George's preferred destination as his free agency looms in the summer of 2018.

One option for the Lakers, sources said, is trying to sell the Pacers on a trade package headlined by the 27th pick -- acquired as part of an agreed-to deal with the Brooklyn Nets on Tuesday -- and the 28th pick in Thursday night's NBA draft, in addition to players such as forward Julius Randle and guard Jordan Clarkson. Indiana, meanwhile, continues to try to pry away Thursday's No. 2 overall pick, despite L.A.'s well-chronicled determination to keep it off limits.

Sources said that David Griffin, in his final few days as Cavaliers general manager, aggressively pursued trades for both Butler and George, seeking to acquire an elite two-way player in the wake of Cleveland's 4-1 NBA Finals defeat to the Golden State Warriors.

But Griffin and Cavaliers owner Dan Gilbert abruptly announced Monday night that they were parting ways, just three days before the draft and less than two weeks before the June 30 expiration of Griffin's contract.

To land either Butler or George, sources said, Cleveland knows it would have to assemble a three-team trade (or one with more teams involved) -- likely costing the Cavs All-Star forward Kevin Love -- to manufacture the top-five draft pick Chicago and Indiana are known to covet in exchange for surrendering their respective best players.

Sacrificing Kevin Love to acquire Paul George, left, or Jimmy Butler -- even for a historically bold team like the Cavaliers -- would be risky if neither player is prepared to make a long-term commitment to the franchise. Brian Spurlock/USA TODAY Sports

ESPN's Dave McMenamin and Brian Windhorst reported Monday night that Gilbert, alongside Cavaliers assistant general manager Koby Altman, would continue to aggressively pursue upgrades to the roster as Cleveland enters the final season in which LeBron James is under contract.

But sacrificing Love to acquire Butler or George -- even for a historically bold team like the Cavaliers -- would be risky if neither player is prepared to make a long-term commitment to the franchise.

George has been widely expected since the All-Star break in February to do anything he can to land with the Lakers in the summer of 2018, while Butler could become a free agent as early as July 2019.