The Big Ten's player of the year will make the announcement Thursday morning, the paper said.
Harris couldn't be reached for comment Wednesday night, and Badger coach Bo Ryan declined comment.
A projected lottery pick, Harris had chosen not to hire an agent when he initially decided to take his chances at the NBA's pre-draft camp. But the 6-foot-3 junior gave up the option of returning to Wisconsin once his stock rose among pro scouts, who see Harris as a potential top-10 pick.
Two teams with top-10 picks, the Cleveland Cavaliers (10th) and the Washington Wizards (5th), are in need of a point guard, and are looking at Harris, who was also a second-team all-Big Ten pick as a sophomore.
In helping the Badgers to a 25-7 record (12-4 Big Ten), Harris averaged 19.5 points, 4.4 assists and 4.3 rebounds.