On trade, he needs a coherent message that rules out protectionism. In his recent foreign-policy speech he talked up negotiations. The master of the art of the deal would be very good at that when it comes to trade. There’s no need for huge tariffs. The goal here is to tear down foreign trade barriers and make China and others play by the rules.

And rather than trade wars and currency manipulation (which includes the U.S.), the world economic system should be anchored by stable and cooperative exchange-rate policies.

On immigration, Trump needs an articulate policy that aims to secure the border and keep out illegals while letting in skilled legal workers. Voters prefer a path to legality (not necessarily citizenship) rather than deportation. And Trump — a cost-conscious business executive — must translate that into curbing the cronyist federal-government leviathan.

There are other issues. But my key thought is that Trump can win by showing a consistent seriousness of purpose and demeanor, pro-growth economic policies and a more realistic national security strategy. He knows, as Ronald Reagan did, that success at home leads to success abroad.