Ryan already is at the center of the campaign and is the world’s foremost expert on the Ryan-Romney plan. No one is more marinated in the facts to which Obama is averse. Ryan has not yet honed his rhetorical skills for communicating complexities to laypersons, but he is a quick study. One drawback is that he is invaluable as chairman of the Budget Committee and in 2015 might become chairman of Ways and Means.

Louisiana’s Gov. Bobby Jindal, 40, was a 20-year-old congressional staffer when he authored a substantial report on reforming Medicare financing. At 24, he became head of Louisiana’s Department of Health and Hospitals, with 12,000 employees and 40 percent of the state budget. Back in Washington at 26, he was executive director of the National Bipartisan Commission on the Future of Medicare. In 1999, he became president of Louisiana’s state university system, which has 80,000 students. In 2001, he served as an assistant secretary of health and human services. He became governor after three years in Congress.

Faux realists will belabor Romney with unhistorical cleverness, urging him to choose a running mate who supposedly will sway this or that demographic cohort or carry a particular state. But are, for example, Hispanics nationwide such a homogeneous cohort that, say, those who came to Colorado from Mexico will identify with a son of Cuban immigrants to Florida (Sen. Marco Rubio)? Do these realists know that, according to exit polls, Nevada’s Hispanic Gov. Brian Sandoval, a Republican, won only about a third of the Hispanic vote in 2010?