37 to exclusively support state and local candidates. Each donor fully and correctly understands that only a small portion of his or her gift will be used “for the purpose of influencing” federal elections. And yet, § 100.57 requires that at least 50% of donations in response to such a solicitation be classified as a hard-money donation subject to the $5000 cap – thereby simultaneously creating a separate $5000 cap on soft-money donations given in response to such a solicitation. This may require a non-profit to decline or return funds it receives for purely state and local elections. That is not permissible under FECA. In short, there is a significant mismatch between these challenged provisions and the FEC’s authority under FECA. Therefore, we conclude that §§ 106.6(f) and 100.57, as well as the provision in § 106.6(c) that applies to administrative expenses, exceed the FEC’s statutory authority.20 20 EMILY’s List separately argues that three of the five regulatory provisions at issue in this case are also arbitrary and capricious under the Administrative Procedure Act. EMILY’s List Br. at 40-44. We are less persuaded by EMILY’s List’s freestanding arbitrary and capricious argument. Putting aside the constitutional and statutory-authority problems with the challenged rules, the provisions are not otherwise arbitrary and capricious. Agencies generally do not violate the APA’s deferential arbitraryand-capricious standard when they employ bright-line rules for reasons of administrative convenience, so long as those rules fall within a zone of reasonableness and are reasonably explained. See, e.g., ExxonMobil Gas Mktg. Co. v. FERC, 297 F.3d 1071, 1084 (D.C. Cir. 2002); WorldCom, Inc. v. FCC, 238 F.3d 449, 461-62 (D.C. Cir. 2001). EMILY’s List does not bring a challenge under either FECA or the APA to § 106.6(c)’s requirement that covered non-profits pay at least 50% of the cost of their generic communications out of their hard-money accounts. See EMILY’s List Br. at 35-44.