Implicit in the choice of Biden, who will turn 78 in 2020, would be that he is unlikely to serve a second term and will train Junior and get him up to speed. Biden’s appeal as a quasi-incumbent is his ability to slide into office with an experienced staff, ready to reset relationships with allies around the world he already has relationships with, and prepared for the challenges from adversaries like the supreme leader in Iran, Russian President Vladimir Putin and Kim Jung Un in North Korea.

After Trump was elected to “shake up things in Washington,” it’s likely voters will turn to yet another opposite force (as Trump was to President Obama, the cool and way-too-calm law professor) and seek a seasoned, competent hand to clean up after the bull that pulverized the china shop. Beto, and other neophytes lining up to run, aren’t likely capable of this complicated repair job.

Biden also remains, as most Republicans will admit privately, the biggest threat to Trump. Because of this, voters at his events often beg him to run. Many Democrats talk about his “obligation.” His endorsement rate was more successful in 2018 than Trump’s or other Democrats, and his crowds in Iowa, where he stumped for Rep.-elect Abby Finkenauer, were larger than those who showed up to see Sens. Bernie Sanders, Cory Booker or Kamala Harris.