In the late 1940s, Hansen also worked as a field organizer for the South Dakota Farmers Union, and later for the Iowa Farmers Union, where he worked under IFU President Frederick William Stover (1898–1990), the former liaison between the USDA and the Roosevelt White House. Stover was a close ally of former Vice President Henry C. Wallace and one of the policy authors of the New Deal's innovative but controversial agricultural reforms. Stover would become Hansen's mentor, teaching him many of the Byzantine intricacies of federal farm policy and remaining a close ally and partner of Hansen's from the 1950s to the 1980s.