With an urgency commensurate with the stakes, temperate Americans of all political persuasions, but especially conservatives, should act together to implement this proposition: JD Vance’s ambitions must be stymied. He says Tucker Carlson (Putin fanboy, Hitler apologist, Churchill disparager, megaphone for Holocaust denial) is his friend, therefore Carlson belongs in the conservative movement. Vance said he will not throw Carlson “under the bus,” because a Vance virtue is acknowledgment of his debts: Carlson ardently lobbied Donald Trump to make Vance his running mate. A president’s character counts because the nation cannot count on the sufficiency of the Constitution’s Madisonian ingenuity....