Trubisky's progression, leadership and overall performance throughout training camp are factors for the decision, the source told ESPN.
Bears coach Matt Nagy had insinuated last weekend that he would refrain from picking between Trubisky and Nick Foles until the Bears opened the regular season on Sept. 13, but he backtracked on Monday, instead suggesting he would make a decision early next week.
Trubisky and Foles have been locked in a battle for the starting job throughout training camp, evenly rotating days on the first team since padded practices began Aug. 17.
In 2018, Nagy's first season as head coach, the Bears went 12-4 as Trubisky passed for 3,223 yards and 24 touchdowns with 12 interceptions and rushed for 421 yards and three touchdowns.
Trubisky, while playing much of last season with a shoulder injury that required surgery in January, ranked 28th in the NFL in Total QBR (39.4), tied for 27th in touchdown passes (17), 21st in passing yards (3,138), 32nd in yards gained per pass attempt (6.1) and 28th in traditional quarterback rating (83.0) as the Bears finished 8-8.
Chicago traded for Foles -- the MVP of Super Bowl LII -- at the onset of the new league year. The Bears later declined Trubisky's fifth-year option and announced an open quarterback competition in training camp.
ESPN's Jeff Dickerson contributed to this report.