Cecil Eugene Schultz, Sr. appeals the 120-month sentence the district court * imposed after Schultz pleaded guilty to a drug-conspiracy charge. Shultz argues an evidentiary hearing is necessary to determine if his coconspirators had indeed pleaded guilty when the government denied him an opportunity to earn a substantial-assistance reduction by providing information. We conclude Schultz failed to make a substantial threshold showing that the government’s refusal was “irrational, in bad faith, or based on an unconstitutional motive.” See United States v. Davis, 397 F.3d 672, 676 (8th Cir. 2005) (per curiam) (quoting United States v. Lieona-Lopez, 163 F.3d 1040, 1042 (1998)). Accordingly, we affirm.