U.S. President Donald Trump is expected to announce the lifting of a federal ban on summer sales of higher-ethanol blends of gasoline on Tuesday in Washington DC ahead of a trip to Iowa the same day, according to two sources familiar with the planning of the event. The move, expected sometime around 3 p.m. on Tuesday, is aimed at helping Republicans in competitive elections in the nation’s farm belt. Iowa is the largest U.S. producer of ethanol. The lifting of the summer ban on so-called E15 gasoline is expected to be coupled with restrictions on trading biofuel credits that underpin the program, the sources said, but it’s unclear whether the restrictions will be detailed […]