What is the test for a motion to sever for abuse of of power?

We review the district court's decision to deny a motion to sever for an abuse of discretion. United States v. Marsh, 894 F.2d 1035, 1040 (9th Cir.1989), cert. denied, --- U.S. ----, 110 S.Ct. 1143 (1990). The test for an abuse of discretion is whether a joint trial would be so prejudicial that the trial judge could exercise his discretion in only one way. United States v. Escalante, 637 F.2d 1197, 1201 (9th Cir.1980), cert. denied, 449 U.S. 856 (1980). The ruling of the trial judge is rarely disturbed on appeal. Id.