Does the withholding of removal statute allow the Attorney General to designate crimes such as assault as particularly particularly serious even if they are not aggravated felonies?

We noted in Delgado v. Holder that [t]here is little question that [the asylum] provision permits the Attorney General, by regulation, to make particular crimes categorically particularly serious even though they are not aggravated felonies. 648 F.3d 1095, 1106 (9th Cir.2011) (en banc) (emphasis in original). However, the withholding of removal statute is notably missing an analogue provision permitting the Attorney General to designate crimes as categorically particularly serious even if they are not aggravated felonies for which the defendant has received a sentence of at least five years.