https://www.gannett-cdn.com/presto/2018/12/14/PWIL/5682b844-9776-4398-8aa5-9b2f28a9dc98-AP18347762575794.jpg delawareonline.com joe biden would be the oldest sitting president if elected in 2020 2019-03-08 he would be the oldest person to become president since Donald Trump took in 2017.. ..…