If the presidential nominating process is the weakest part of our political system, and, perhaps not coincidentally, one not referenced by the founders, the vice presidential selection process comes in solidly in second place. Some might even argue it’s a contender for the top spot.

That’s been particularly the case in the two most recent election cycles. The 2016 election, with Republican and Democratic nominees age 70 and 69 on Election Day, elevated the actuarial odds of a vice president succeeding to the presidency to the highest level in history.