5 Myths About the Vice Presidency

4. Candidates should think "outside the box."

For candidates, as for housecats, the box is there for a reason.

Those who aren't fantasizing about a bipartisan ticket often dream that a nominee will look outside politics altogether for his or her deputy. (Former Hewlett-Packard chief Carly Fiorina is one name bandied about this year.) Washington loves no cliche more than the cliche of Washington's bankruptcy -- the myth that only someone with no political experience, usually a mogul or a financier, can fix our political mess. (It's a myth that got the nutty H. Ross Perot 19 percent of the vote in 1992.) But it hasn't happened yet -- and probably won't. Occasionally an Arnold Schwarzenegger or a Bloomberg succeeds in high office without prior government experience. But most politicians canny enough to get a presidential nomination know that the fall campaign isn't the place for a novice to be learning the game.

5. All of this is beside the point: The choice of a running mate doesn't matter.

The aphorisms are legion: John Adams called the vice presidency "the most insignificant office that ever the invention of man contrived or his imagination conceived." Nelson Rockefeller called it "stand-by equipment." John Nance Garner, we often hear, said that the job wasn't "worth a bucket of warm spit," though he didn't actually say "spit." But these days, the vice presidency is worth a lot. Ever since Nixon held the office under Dwight Eisenhower, the office has been growing in power, reaching unprecedented influence under Dick Cheney.

But, does anyone vote based on the veep? The kibitzing over a nominee's choices is clearly out of proportion to the importance of the selection. Given that George H.W. Bush survived the calamitous selection of Dan Quayle in 1988, it's hard to argue that even a bad choice can sink a candidacy -- though George McGovern's jettisoning of Tom Eagleton in 1972 sure didn't help his already floundering campaign.

Still, significant numbers of voters tell pollsters that the candidates' veep choices help them decide how to vote in the fall. A March poll by SurveyUSA showed that between 12 and 40 percent of voters, depending on the state and the top of the ticket, said that the vice presidential choice would influence them. And more recent polls show huge swings in how various states break depending on the choices. (In New Mexico, for example, McCain-Huckabee beats Obama-Hagel by 17 points, but McCain-Pawlenty loses to a pairing of Obama and former senator John Edwards by nine points.)

That kind of self-reporting is unreliable, of course. Name recognition alone, for example, probably accounts for the boost that Edwards gives Obama in some polls. But some political scientists do surmise that the choice can shift the popular vote by a smidgen -- and even 1 or 2 percent can be enough, in the kinds of close presidential elections we've had in 2000 and 2004, to make all the difference.

David Greenberg is a professor of history and media studies at Rutgers University, a columnist for Slate and the author of "Nixon's Shadow: The History of an Image."