The Rockefeller family was instrumental in the post-Civil War transformation of the GOP into a pro-free market party. John D. Rockefeller, Sr. and Marcus Hanna and their associates provided almost all of the campaign funding for William McKinley's 1896 presidential victory (McKinley was the first president who could truly be considered a conservative).
However, in the past several decades, the Rockefellers have evolved into either RINOs or 'Rats. They seem to use their wealth to "buy" political office in economically "less advantaged" states like West Virginia and Arkansas, and the Rockefeller Foundation has become a bastion of leftist funding.