A network of radical conservative think-tanks spanning all 50 states is planning direct marketing campaigns targeted personally at union members to encourage them to quit. The secret push, the group hopes, could cost unions up to a fifth of their 7 million members, lead to the loss of millions of dollars in income and undermine a cornerstone of the American middle-class.

The group is funded by such billionaire conservative donors as the Koch brothers and the Walton Family Foundation that stems from the Walmart fortune.