5 U.S.C. § 1502: Influencing elections; taking part in political campaigns; prohibitions; exceptions

use his official authority or influence for the purpose of interfering with or affecting the result of an election or a nomination for office; directly or indirectly coerce, attempt to coerce, command, or advise a State or local officer or employee to pay, lend, or contribute anything of value to a party, committee, organization, agency, or person for political purposes; or if the salary of the employee is paid completely, directly or indirectly, by loans or grants made by the United States or a Federal agency, be a candidate for elective office. A State or local officer or employee retains the right to vote as he chooses and to express his opinions on political subjects and candidates. the Governor or Lieutenant Governor of a State or an individual authorized by law to act as Governor; the mayor of a city; a duly elected head of an executive department of a State, municipality, or the District of Columbia who is not classified under a State, municipal, or the District of Columbia merit or civil-service system; or an individual holding elective office.