The Obama administration is boosting the amount of corn-based ethanol and other renewable fuels in the U.S. gasoline supply despite sustained opposition by an unusual alliance of oil companies, environmentalists and some GOP presidential candidates. The Environmental Protection Agency on Monday issued a final rule designed to increase production of ethanol to be blended with gasoline through 2016, a decision that could reverberate in Iowa's crucial presidential caucuses. The agency said it will require more than 18 billion gallons of renewable fuels in 2016, most of it ethanol. The amount is less than was set in a 2007 renewable fuels...