Likewise, it’s important to differentiate between politicians who can live peacefully with (if not embrace) those things for which they are parodied. For instance, few public figures have been spoofed as vigorously as Senator Hillary Rodham Clinton. Everything from her suspected ambition to her laugh has been fair game. Yet few would dismiss her as anything less than formidable. She’s hardly defined by her foibles. In her presidential campaign, she did a fair job of getting in on the joke, laughing at herself in several settings and appearing with some of her top teasing tormenters (like Jon Stewart on “The Daily Show” and Amy Poehler on “Saturday Night Live”).

New-on-the-scene politicians are more prone to being overtaken by their parodies.

“Vice presidents can be particularly vulnerable,” said Mr. Lichter, who mentions Vice President Dan Quayle as one who never fully recovered from the mockery that greeted his debut in 1988. It can also extend to running mates, like Adm. James Stockdale, Ross Perot’s No. 2, who today is better remembered for his doddering debate performance in 1992 than his heroic career. Politicians at the center of sex scandals enter a particularly unforgiving punch-line purgatory. (You think Mr. Stewart or Conan O’Brien are ever going to talk about John Edwards, Gary Hart or Eliot Spitzer for their policy ideas?)

On the other hand, Vice President Dick Cheney has provided a lifetime supply of heart-attack and hunting-accident humor (such fun genres!), but will clearly go down as a serious, contentious and multidimensional figure in history. “There is a tipping point that politicians reach,” said Bob Orben, who was head of White House speechwriting for Gerald R. Ford before writing comedy for the likes of Red Skelton and Dick Gregory.

Mr. Orben refers to America’s “comedy establishment,” which he said was much more powerful today than it was in Mr. Ford’s day. “You only had to overcome Johnny Carson back then,” he said, and “Saturday Night Live,” too (Chevy Chase’s portrayal of Mr. Ford as physically clumsy marked the reputation of Mr. Ford, a former college football player, forever).