Westbrook's agent, Thad Foucher, is planning to file the paperwork Tuesday, sources said. Westbrook has a Wednesday deadline on his option.
Westbrook, a nine-time All-Star and 2017 NBA Most Valuable Player, is entering the final season of his original five-year, $206 million contract.
The Lakers are counting on Westbrook to have a comeback season under new coach Darvin Ham. Westbrook has told ESPN in recent weeks that he's enthusiastic about getting to know Ham.
After 11 seasons in Oklahoma City, Westbrook completed his fourth season for a fourth team a year ago -- including stops with Houston and Washington. Westbrook, who averaged 18.5 points, 7.4 rebounds and 7.1 assists a year ago, played only 21 games with LeBron James and Anthony Davis, largely because of injuries. The Lakers were 11-10 in those games and finished the season out of the playoffs with a 33-49 record.