 But I'm only three years older than Trump, number one. And number two, my mental acuity has been pretty damn good. Biden then touted his record in office. Tamara Keith, NPR News. Former President Donald Trump has chosen Republican Senator J.D. Vance of Ohio as his vice presidential running mate. NPR's Danielle Kurtzleben is at the Republican National Convention in Milwaukee. She says Vance is 39 and a first-term senator.