Anti-union forces are launching a nationwide campaign urging public sector workers to opt out of union membership and stop paying dues, according to documents obtained by The Guardian. The campaign, designed to defund and defang unions, is led by the State Policy Network, a group of right-wing think tanks funded by the Koch brothers and the Walton Family Foundation. It’s designed to cost unions millions of dollars and, as The Guardian describes it, “undermine a cornerstone of U.S. progressive politics.” Documents include this gem: “Well run opt-out campaigns can cause public-sector unions to experience 5 to 20 percent declines in membership.”