From the Summary: "To help curb corruption in the political process and safeguard First Amendment rights to freedom of speech and association, Congress has enacted laws that regulate political campaign contributions. These laws include political patronage and campaign finance laws. Federal political patronage laws serve to protect federal employees--including congressional staff--from being required to make campaign contributions as a condition of employment. These criminal laws include a prohibition on Members of Congress, congressional candidates, and congressional staff from knowingly soliciting federal office campaign contributions from another such officer, employee, or person receiving compensation for services from money derived from the U.S. Treasury. [...] Federal campaign finance laws regulate campaign contributions made to congressional candidates by establishing limits, source restrictions, and disclosure requirements. The Federal Election Campaign Act (FECA) defines a contribution to include money or anything of value that is made for the purpose of influencing any federal election. A contribution can be distinguished from an expenditure in that a contribution involves giving money to an entity, such as a candidate's campaign committee, while an expenditure involves spending money directly for advocacy of the election or defeat of a candidate. For knowing and willful violations of FECA, criminal penalties may be imposed."
CRS Report for Congress, R46521
Congressional Research Service: https://crsreports.congress.gov/