The fuel most Americans rarely think about is becoming a new hurdle for President Donald Trump’s push to make housing more affordable, as the Iran war raises costs for construction sites.With the midterm elections approaching, the diesel surge underscores the political tension facing Trump and congressional Republicans as they promise to bring down housing costs while war-driven energy prices add new pressure to home construction.Builders are already wrestling with expensive financing, labor, materials and costs tied to regulations and permitting that Republicans have pledged to reduce. Becaus...