Two of the Nationals' other top pitching prospects, right-handers Reynaldo Lopez and Koda Glover, will not be in the proposed deal, the source told Bowden. The structure of the deal was first reported by Fox Sports.
Earlier Monday, White Sox general manager Rick Hahn said he wasn't budging in his asking price for Sale, likely the biggest prize of the winter trade market because of his All-Star résumé and relatively modest contract.
"When you have negotiations with other clubs about potential trade fits, you have to have that line you aren't going to go below; otherwise you're compromising too much in terms of value," Hahn said Monday afternoon.
Sale, 27, is coming off his fifth straight All-Star season in 2016, when he finished 17-10 with 233 strikeouts in 226 innings pitched.
But he is on a very team-friendly deal that will pay him $12 million in 2017, with club options of $12.5 million for 2018 and $13.5 million for 2019.
"You've seen what this guy has done over the years," Hahn said Monday. "We realize this is an elite-level talent. A rare commodity in this league."
Information from ESPN's Jesse Rogers was used in this report.
Nationals on verge of acquiring Sale
The Baseball Tonight crew reacts to Jim Bowden's report that the Nationals are close to acquiring Chris Sale from the White Sox and what that could mean for Washington.