… If it’s a performance, then it can be switched on and off as needed. You can trace this tactic as far back as, improbably, Franklin D. Roosevelt. In her book “Voting Deliberatively: F.D.R. and the 1936 Presidential Campaign,” Mary E. Stuckey writes that, during the summer months before the election: “F.D.R. concentrated on being presidential. So determinedly nonpolitical was he, in fact, that Roosevelt didn’t actually acknowledge he was running for re-election until late September.” But when he finally did campaign, Roosevelt “came out swinging” against his Republican opponents. In Stuckey’s rendering, “presidential” requires remaining above the fray that running for president invariably requires leaping into.

Richard Nixon also understood the power of performance. Gil Troy, in his book “See How They Ran,” captures the sleight-of-hand that Nixon deployed to finally land the job in 1968. His famously moist televised debate performance in 1960 haunted him; so did his failure to seem as persuasively presidential — as good-looking, basically — as John F. Kennedy. Eight years later, Troy writes, things had changed: “Following his advisers and acting presidential, Nixon snatched the Republican nomination. His platitudes offered a soothing alternative to the mounting Vietnam protests. Richard Nixon, the man of a thousand resentments, the pit bull of American politics, would again pose as an apostle of unity and peace.”

Two terms later, John Osborne, writing for The New Republic, noted that President Gerald Ford’s struggles during the 1976 Republican primaries had left his campaign with only one option. “His best hope of nomination and election lies in his being as presidential as possible,” Osborne wrote. In hindsight, it seems as if that hope had already been snatched away by Chevy Chase’s murderous impression of Ford as a buffoon on “Saturday Night Live.” His primary challenger — Ronald Reagan, the master of modern presidential performance — would never have gone out like that. He got out in front of caricaturists by mocking himself (and his opponents) while simultaneously understanding how to “star” in a televisual campaign and deftly time a one-liner during a debate.

By the late 20th century, “presidential” had become entirely bound up in technological savvy, and Reagan, as could be expected from a former president of the Screen Actors Guild, was an artist when it came to optics. Brian Balogh, a professor at the Miller Center of Public Affairs at the University of Virginia and co-host of the radio show “BackStory With the American History Guys,” told me that “Reagan’s stroke of genius was to continue running against the establishment while he was actually the president.” This was a man who, during his 1984 re-election bid, had Air Force One land just outside the Daytona International Speedway to attend the Fourth of July Firecracker 400. “A lot of people,” Balogh said, “would say that was unpresidential.” A decade later, the nation would be in the midst of an ongoing fit over all things “unpresidential,” thanks to Bill Clinton’s sax playing, his stated preference for briefs over boxers (on MTV!), his extramarital affair….