Do vice presidential picks matter? Conventional wisdom argues they have limited electoral impact.
But a vice presidential pick does matter in a particular way to elections. It suggests the strategy and tactics a campaign will pursue. The pick might complement the ticket, like Al Gore did for Bill Clinton in 1992, or the pick might balance the ticket, like Mike Pence did for Donald Trump.
So Joe Biden's electoral fate may well hinge on this decision. In our polarized era, where turnout determines election victors and each party's coalition has become more locked in, ticket-balancing picks for vice president can be helpful in mending primary wounds and generating excitement for the coalition in the general election.
That is why Biden should select for his running mate a ticket balancer.
Now, the temptation for Biden to pick a ticket "complementer" will be high. All the conventional wisdom suggests that ticket complementers "do no harm" because they are, essentially, prototypes of the presidential nominee.
By contrast, ticket balancers offer voters something the main nominee lacks and often are meant to motivate a group within the coalition with which the nominee has struggled to gain traction. Balancers are perceived to be riskier, especially since John McCain's selection of Sarah Palin in 2008.
Hillary Clinton is often castigated as running a terrible, horrible, no good, doomed campaign. She actually ran a perfectly fine campaign — but strategically speaking, it was the wrong kind of campaign. It was based on the flawed assumption that a significant portion of American conservatives would not, simply could not, vote for Donald Trump.
But on Election Day, 90% of Republicans voted for him; Clinton also failed to carry independents, despite a campaign structured mostly on winning them over.