Biden has four great options for a black female running mate. One is his best.

Presumptive Democratic presidential nominee Joe Biden has said he will choose a woman as his vice-presidential running mate. In a previous post, I argued that she needs to be African American. And I stressed an often ignored point: Winning the Midwestern states Hillary Clinton lost in 2016 and appealing to African American voters are not mutually exclusive.

Now comes the parlor game of figuring out who that black woman should be.

Biden knows how important it is to have an empowered governing partner who commands respect inside and outside the...