The Obama administration delivered a blow to the corn industry on Monday, easing the amount of ethanol the nation must consume below the levels Congress had set nearly a decade ago -- and potentially laying a political stumbling block for Hillary Clinton in Iowa. The ethanol pullback comes as a slump in gasoline consumption and a domestic energy boom have lessened the fears of dependence on Mideast oil that inspired lawmakers to create the mandate during the George W. Bush administration. But the mandate is still popular in Iowa, home of the nation's first presidential caucus, where corn and ethanol...