If I’m not mistaken, President Reagan created it to go after organized crime.
It was passed in its initial form in 1970. Ironically, Joe Biden played a major role while chairman of the judiciary committee in introducing at least one law related to public corruption; Title 18 U.S. Code Section 1346:
Section 1346. Definition of "scheme or artifice to defraud"
For the purposes of this chapter, the term "scheme or artifice to defraud" includes a scheme or artifice to deprive another of the intangible right of honest services.