WASHINGTON/MONTOURSVILLE, Pa. (Reuters) - U.S. President Donald Trump, facing a potentially difficult path to winning a second term in November 2020, on Monday told supporters in Pennsylvania that his trade war had strengthened the battleground state"s steel industry and jobs. Although Trump does not launch his re-election bid officially until next month, his appearance at a raucous rally in an airport hangar in northeastern Pennsylvania, using Air Force One as a backdrop, had the hallmarks of a campaign event. "Sleepy Joe said that he"s running to "save the world." ... He"s going to save every country but ours," Trump said.