It shall be unlawful for any political committee or any member, employe or agent thereof, or for any public officer or employe, or any other person whatsoever, directly or indirectly, to demand from any public officer, subordinate or employe holding any office or position of honor, trust or profit under this Commonwealth, or otherwise engaged or employed in the service of the Commonwealth, or employed by, or in any way engaged in the service of, any political subdivision, or from any person receiving any public assistance whatsoever from the Commonwealth or the United States, directly or through employment on public works, or any person, association or corporation desiring or having a contract with, or a certificate, license or permit from, the Commonwealth or any political subdivision, any assessment or percentage of any money or profit, or their equivalent in any thing of value, with the understanding, express or implied, that the same may be used or shall be used for political purposes: Provided, however, That nothing in this act contained shall be construed to prohibit voluntary contributions to any political committee or organization for legitimate political and campaign purposes to the extent such contributions are not prohibited by law.