EVEN AS HE struggles to come up with the roughly $450 million he needs to pay the state of New York in the wake of a colossal civil judgment against him, Donald Trump’s lock on the support of the Republican Party faithful is as secure as ever. He has clinched the presidential nomination and holds a narrow – yet commanding in the Electoral College system – lead over the incumbent, Joe Biden, in the polls in nearly all of the battlegrounds that will determine the result in November. Attention will soon turn to the question of whom Trump will select...