Fredreka Schouten for USA Today:

A group tied to billionaire Charles Koch has unleashed an aggressive campaign to kill a ballot measure in South Dakota that would require Koch-affiliated groups and others like them to reveal their donors’ identities — part of a sustained effort by his powerful network to keep government agencies and the public from learning more about its financial backers.

Americans for Prosperity, the largest activist group in the policy and political empire founded by industrialist Koch and his brother, David, launched a coalition this year to fight Initiated Measure 22, which calls for public disclosure of donors who fund advocacy efforts, the creation of a state ethics commission and public financing of political campaigns. It also limits lobbyists’ gifts to elected officials and lowers the amount of campaign contributions to candidates, parties and political action committees.