DES MOINES — Iowa’s most powerful state and federal government leaders have an ally in the White House thanks to political unity forged in the 2016 elections.There is a Republican president and a GOP-led Congress to team with Iowa Republicans in both of the state’s U.S. Senate seats and the governor’s office, as well as its own GOP-led Iowa Legislature.That Republican symmetry has helped produce significant conservative reforms on the federal and state levels.But while President Donald Trump’s administration completed Republicans’ power trifecta in the nation’s capital, it also has, on occasion, put Iowa leaders on the defensive against their own party.Trump administration moves, for example, to weaken the federal mandate for ethanol in the nation’s fuel supply and on international trade have caused concerns in Iowa.