FILE – In this Jan. 24, 2014 file photo, Republican National Committee Chairman Reince Priebus is seen at the RNC winter meeting in Washington. Millionaires and billionaires are increasing their influence in federal elections, forcing the parties to play more limited roles, and raising questions about who sets the agenda in campaigns. In a handful of key Senate races, the biggest and loudest players so far are well-funded groups that don’t answer to any candidate or political party-such as the conservative billionaire Koch brothers. Some veteran lawmakers worry about the clout of the Republican and Democratic parties, which have dominated U.S. politics since the Civil War. The recent Supreme Court ruling appears unlikely to reduce the role that outside groups are playing. (AP Photo/Susan Walsh, File)