On his Web site, Cook promises fans he'll do everything possible to reschedule the show at Owens Community College outside Toledo that had been planned for Wednesday.
The visitation is that day for the singer's 37-year-old brother, Indiana attorney Adam Cook, who died Saturday after a more than decade-long fight with brain cancer. The viewing will be followed on Thursday by a private service at a Terre Haute, Ind., cemetery.
David Cook says his other concerts will go on as scheduled because his brother never wanted his illness to affect anyone. The reigning "Idol" champ has a show Tuesday night in Louisville, Ky., and performs Friday in Akron, Ohio.