MILWAUKEE (AP) — JD Vance used his Wednesday night address to the Republican National Convention to share the story of his hardscrabble upbringing and make the case that his party best understands the challenges facing struggling Americans. The 39-year-old Ohio senator is a relative political unknown. In his first prime-time speech since becoming the nominee for vice president, Vance spoke of growing up poor in Kentucky and Ohio, his mother addicted to drugs and his father absent, and how he later joined the military and went on to the highest levels of U.S. politics.