State campaign finance law that seems facially underinclusive given stated aims is nonetheless lawful, given presumption of statute's legitimacy. Court did not abuse its discretion in holding that legislative caucuses were the functional equivalents of political parties for purposes of the law.
http://media.ca7.uscourts.gov/cgi-bin/rssExec.pl?Submit=Display&Path=Y2018/D09-13/C:16-3585:J:Sykes:aut:T:fnOp:N:2217703:S:0
Since 2011. An occasional commonplacing of the U.S. Circuit Courts of Appeal.
Neither an authoritative statement of the law nor legal advice. Quick work.