There is an uncanny symmetry in the two presidential candidates’ choice of vice presidential running mates. There are a few superficial differences — Republican J.D. Vance is 40, Democrat Tim Walz 60, Vance is bearded, Walz balding.

The similarities are greater, and they go beyond the fact of their military service. Both were chosen by principals in moments of exuberance, Donald Trump after he’d walloped Joe Biden in debate and survived an assassination attempt, Kamala Harris after she’d outperformed expectations and surged to a lead in the polls.