This optimism vs. anger divide is one of the deepest of the 2016 campaign, almost as deep as the one between the two parties. The question is: Which school has the best fix on America’s mood today—the one that says great days are within reach, or the one that says you’re being shafted by elitists and it’s time to strike back?

Hope usually is a better political message than is despair, and that certainly is Mr. Bush’s calculation. “I think that is the real dividing line between the candidates,” says one Bush adviser. “Who is running on grievance, with a rearview mirror and list of complaints, and who is running forward with optimism and a positive conservative vision?”

In a sense, Mr. Bush is offering the 2016 version of Ronald Reagan’s “morning in America” message of a bright future that lies just ahead for the U.S. But it wasn’t just Mr. Reagan in 1980 and 1984 who found that optimism had resonance. Bill Clinton won in 1992 with a message that Hope wasn’t merely the name of his Arkansas hometown, but also the idea he would bring to Washington. Barack Obama won in 2008 after writing a best-seller titled “The Audacity of Hope.”