Mr. Ryan has also performed better on the national stage than even many of his supporters anticipated. Even Democrats have had to concede he’s no lightweight and does his homework. He has put a new, youthful face on the Republican Party, and his earnest enthusiasm is a walking refutation of Democratic claims that he’s a Randian radical. He looks and sounds like Janesville.

The latest assault—and the one likely to persist through November and beyond—is that Mr. Ryan won the genetic lottery, has no feeling for his fellow man, and thus wrote a budget that grinds down the less fortunate. These attacks will be on full display next week in Charlotte, especially now that it has become clear that Mr. Romney might win.

The best response to these attacks is for Mr. Ryan to keep showcasing his natural optimism and Midwest equanimity. And for both Messrs. Ryan and Romney to focus on their plans to restore growth and lift middle-class incomes…

Mr. Romney has had a hard time inspiring enthusiasm less because of his personality than because his candidacy has seemed more a personal crusade than a movement. In choosing Mr. Ryan, Mr. Romney gave Americans hope that he is trying to rally the country for the larger purpose of greater freedom and national revival.