In 1954, to help stop his political opponents, then Senator Lyndon Johnson introduced an amendment to the tax code to bar tax-exempt entities from involvement in political campaigns. The "Johnson Amendment" was passed and became part of federal law:
"Corporations . . . organized and operated exclusively for religious, charitable, scientific, testing for public safety, literary, or educational purposes . . . [can]not participate in, or intervene in (including the publishing or distributing of statements), any political campaign on behalf of (or in opposition to) any candidate for public office."
Thus, the Johnson Amendment prevents such non-profit organizations (including religious non-profits and churches) from taking action or making statements for or against a candidate for public office if they want to remain tax exempt.