What is the test for a motion to reduce sentence for abuse of discretion?

We review the denial of a Rule 35(b) motion to reduce sentence for abuse of discretion. United States v. Thayer, 857 F.2d 1358, 1359-60 (9th Cir.1988). On review we must determine whether the denial of the motion "was based on a consideration of relevant factors and whether there has been a clear error of judgment." United States v. Ruffen, 780 F.2d 1493, 1495 (9th Cir.), cert. denied, 479 U.S. 963 (1986). "The function of Rule 35(b) is 'simply to allow the district court to decide if, on further reflection, the original sentence now seems unduly harsh.' " United States v. Smith, 650 F.2d 206, 208 (9th Cir.1981) (quoting United States v. Maynard, 485 F.2d 247, 248 (9th Cir.1973). In essence, a Rule 35(b) motion to reduce sentence is a plea for leniency. Thayer, 857 F.2d at 1360.