MEMORANDUM **

Washington state prisoner Leopold Cardenas appeals from the district court’s order denying his 28 U.S.C. § 2254 habeas *178corpus petition challenging his jury conviction for two counts of robbery while armed with a deadly weapon. We have jurisdiction under 28 U.S.C. §§ 1291 and 2253, and we affirm the district court.

We reject Cardenas’ contention that his due process rights were violated when the prosecution failed to disclose evidence that could be used to impeach a key witness. The state courts’ determination of this issue was not an unreasonable application of clearly established federal law. See 28 U.S.C. § 2254(d); see also Weighall v. Middle, 215 F.3d 1058, 1062 (9th Cir. 2000). As the testimony of Cardenas and another individual provided sufficient evidence to impeach this witness, the undisclosed evidence was immaterial and cumulative. See United States v. Vgeri, 51 F.3d 876, 880 (9th Cir. 1995); see also Ortiz v. Stewart, 149 F.3d 923, 936 (9th Cir. 1998) (same).

To the extent that Cardenas’s brief raises uncertified issues, we construe his contentions as a motion to expand the Certificate of Appealability, and deny the motion. See 9th Cir. R. 22-l(e); see also Hiivala v. Wood, 195 F.3d 1098, 1104-05 (9th Cir. 1999) (per curiam).

AFFIRMED.