Joe Biden is now the presumptive Democratic nominee for president, after Bernie Sanders suspended his campaign Wednesday morning. The next big question in the race - beyond when and how Biden will be formally nominated amid a pandemic, of course - is who is going to fill out the ticket as Biden’s vice presidential running mate. The pick carries unusual importance, especially given Biden, who will turn 78 shortly after Election Day, would be the oldest president ever elected by far. We already know one thing about that pick: It will be a woman, as Biden pledged in a recent...