Although much smaller compared to their peak membership in the 1950s, American unions remain a political factor, both through mobilization of their own memberships and through coalitions with like-minded activist organizations around issues such as immigrant rights, trade policy, health care, and living wage campaigns. Of special concern are efforts by cities and states to reduce the pension obligations owed to unionized workers who retire in the future. Republicans elected with Tea Party support in 2010, most notably former Governor Scott Walker of Wisconsin, have launched major efforts against public sector unions due in part to state government pension obligations (even though Wisconsin's state pension is 100% funded as of 2015) along with the allegation that the unions are too powerful. The academic literature shows substantial evidence that labor unions reduce economic inequality. Research indicates that rising income inequality in the United States is partially attributable to the decline of the labor movement and union membership.