18 U.S.C. § 603: Making political contributions

It shall be unlawful for an officer or employee of the United States or any department or agency thereof, or a person receiving any salary or compensation for services from money derived from the Treasury of the United States, to make any contribution within the meaning of section 301(8) of the Federal Election Campaign Act of 1971 to any other such officer, employee or person or to any Senator or Representative in, or Delegate or Resident Commissioner to, the Congress, if the person receiving such contribution is the employer or employing authority of the person making the contribution. Any person who violates this section shall be fined under this title or imprisoned not more than three years, or both. For purposes of this section, a contribution to an authorized committee as defined in section 302(e)(1) of the Federal Election Campaign Act of 1971 shall be considered a contribution to the individual who has authorized such committee. The prohibition in subsection (a) shall not apply to any activity of an employee (as defined in section 7322(1) of title 5 ) or any individual employed in or under the United States Postal Service or the Postal Regulatory Commission, unless that activity is prohibited by section 7323 or 7324 of such title.