Gherezgiher Tecle Embeye, a native of Ethiopia and citizen of Eritria, petitions for review of an order issued by the Board of Immigration Appeals (BIA) dismissing his appeal from the immigration judge’s (IJ) decision to deny his applications for asylum, withholding of removal, and relief under the Convention Against Torture (CAT). Embeye challenges the finding of both the IJ and BIA that he lacked credibility. Embeye also argues that he has established his eligibility for asylum or withholding of removal. Embeye has abandoned any argument he might have raised regarding the denial of his motion for protection under the CAT by failing to challenge the decision in his petition for review. See Witter v. INS, 113 F.3d 549, 554 (5th Cir. 1997).

Both issues raised by Embeye would require this court to review and overturn a determination by the IJ and BIA as to his credibility as a witness. We may not “substitute our judgment for that of the BIA or IJ with respect to the credibility of the witnesses or ultimate factual findings based on credibility determinations.” See Chun v. INS, 40 F.3d 76, 78 (5th Cir. 1994).

Accordingly, Embeye’s petition for review is DENIED.