The Olmsted Locks and Dam project is under construction on the Ohio River between Illinois and Kentucky. U.S. Army Corps of Engineers hide caption

itoggle caption U.S. Army Corps of Engineers

Tea Party activists gather on Capitol Hill in 2011. A surge in applications for 501(c)(4) status in recent years has revealed sometimes murky and contradictory rules governing the political activities of tax-exempt groups. Brendan Smialowski/AFP/Getty Images hide caption

itoggle caption Brendan Smialowski/AFP/Getty Images