Which voter groups give you the biggest payoff at the polls?

One of the most puzzling things about Nate Silver’s new method for evaluating Democratic presidential contenders – or as Libby Watson calls it, “the weird pentagon chart thing” – is his choice of “key” constituencies. Silver insists that his groups –

• Party Loyalists

• The Left

• Millennials and Friends

• Black Voters, and

• Hispanic (with perhaps Asian) voters

– were…