Campaign Finance: Federal Framework, Agency Roles and Responsibilities, and Perspectives [open pdf - 4MB]
From the Document: "Campaign finance is the raising and spending of money to influence electoral campaigns at the federal, state, and local levels. The Federal Election Commission (FEC) reported that in 2017 and 2018, candidates, party committees, and political action committees (PAC) raised about $8.6 billion and spent about $6 billion on activities associated with federal elections. With such large sums of money involved, concerns about limiting the potential for political corruption and providing transparency to voters, while protecting free speech, have been at the heart of campaign finance law."
Government Accountability Office: https://www.gao.gov/