Whether the government must establish a proposal for unlawful sexual activity to satisfy the substantial step element of attempted sexual enticement of a minor under 18 U.S.C. § 2422(b)

When proving a violation of 18 U.S.C. § 2422(b) (attempted sexual enticement of a minor), must the government establish that the defendant either made or accepted a proposal for unlawful sexual activity involving the minor in order to satisfy the crime’s substantial step element? ii