According to Joe Cowley of the Chicago Sun-Times, Butler is "all but fed up with the nonchalant attitude of his younger teammates," specifically center Karl-Anthony Towns.
Butler has one year remaining on his contract before he can decline his player option and become a free agent in 2019.
The 28-year-old Butler was traded to the T'Wolves last offseason after spending the first six seasons of his career with the Chicago Bulls.
Butler performed well in his first season with the Timberwolves, as he averaged 22.2 points, 5.3 rebounds, 4.9 assists and 2.0 steals per game.
He also helped lead them to their first playoff berth since 2003-04.
Despite Butler aiding in Minnesota's turnaround, Cowley reported that he has plans for the future that don't include the T'Wolves.
Like Butler, Irving can become a free agent after the 2018-19 campaign.
Butler has played playoff basketball in six of his seven NBA seasons, but he has never advanced past the second round.
The T'Wolves are brimming with young talent in the form of Towns and Andrew Wiggins, but they barely made the playoffs in 2017-18 as the No. 8 seed.
With the West getting even better due to LeBron James' decision to sign with the Los Angeles Lakers, Minnesota's future may not be as bright as initially thought.
If Butler decides to opt out and leave after next season, a reshuffling of the roster around Towns could be in order.