Scott Farris / Special to The Washington Post

Every presidential election cycle, once a party’s nominee becomes clear, we focus on the veepstakes.

Whom will Mitt Romney choose? Will he play it safe with a traditional pick, such as Walter Mondale in 1976 or Jack Kemp in 1996? Or take a chance, as John McCain did with Sarah Palin in 2008?

Either way, there is no evidence that a running mate plays a great part in voters’ decisions. But that can’t stop us from considering these five misconceptions about the office:

1. Being the vice presidential nominee is a steppingstone to the presidency.

This is true, if your ticket wins. Fourteen vice presidents have become president. Five were elected in their own right; eight ascended to the office when the president died of natural causes or assassination; and one moved up when the president resigned. The odds of a vice president becoming president are about 1 in 3.

But the odds are far worse for the vice presidential nominee on a losing ticket. Only one, Franklin Roosevelt, who was James Cox’s vice presidential choice in 1920, went on to be elected president — and that wasn’t until 12 years later.

In fact, only one other losing vice presidential nominee later won his party’s presidential nod: Bob Dole, Gerald Ford’s running mate in 1976. And Dole did not become the GOP presidential nominee until his third try, when he lost to President Bill Clinton in 1996.

Being the losing VP candidate can end a promising political career, though not all have such a comedown (if you want to take the negative view of her post-2008 career) as Palin, who later resigned as governor, or John Edwards, who’s been tarnished by a high-profile affair and a criminal trial. Still, the prospects for a losing VP pick are glum enough that potential nominees might heed Daniel Webster, who declined the offer to run for vice president several times, saying: “I do not propose to be buried until I am dead.”

2. A VP nominee’s most important role is to balance the ticket.

This is true sometimes, as when a young and relatively inexperienced Barack Obama picked 36-year Senate veteran Joe Biden in 2008, or when Washington insider Dick Cheney suggested himself to George W. Bush in 2000 to counterbalance Bush’s perceived lack of gravitas and foreign policy experience.

But one of the most successful contemporary political pairings was of two wonkish, 40-something, white Southerners: Bill Clinton and Al Gore in 1992. Gore’s selection reinforced the message of generational change that Clinton wanted to send as he unseated the last president of the World War II generation, George H.W. Bush.

Clinton and Gore also reported that they had great “chemistry” and enjoyed campaigning together, qualities said to also be high on Romney’s list. But will he find his political soul mate in someone comfortably familiar, such as Ohio Sen. Rob Portman, or someone younger and ideologically edgier, such as Wisconsin Rep. Paul Ryan?

3. A VP nominee can carry a key swing state.

This has not happened since 1960, when Lyndon Johnson, ahem, helped John Kennedy win Texas. But that was a time when political machines could still have a major impact on turnout.

Since then, presidential nominees have generally ignored this consideration, or it has not worked. Massachusetts Gov. Michael Dukakis attempted to revive the Kennedy-Johnson “Boston-Austin Axis” in 1988, but having Sen. Lloyd Bentsen on the ticket could not make Texas a Democratic state again. Nor could Edwards deliver his native North Carolina for John Kerry in 2004.

The near-abandonment of this strategy has been a boon to VP nominees from less populous states, such as Cheney, of Wyoming, and Palin, of Alaska. Sen. John Thune, of South Dakota, should take heart.

4. A bold VP choice can energize an otherwise moribund campaign.

This seemed to happen when McCain chose Palin, which electrified the Republican base, but McCain still lost decisively, and Palin’s miscues and perceived combative nature may have negated any sizzle she gave the ticket.

Presidential candidates do not want to be upstaged by their running mates. They think the election is about them — and it is, as surveys consistently show. History reinforces the polling; selections such as Spiro Agnew and Dan Quayle received heavy media criticism, but each was on the winning side.

But sometimes when the odds are long, a presidential nominee believes he can boost his chances with an exciting VP choice. That was part of Mondale’s thinking in 1984 when he selected Geraldine Ferraro, a New York congresswoman, to be the first female vice presidential nominee for a major party. But this was after the National Organization for Women demanded that Mondale select a woman, muting the impact of his choice. He lost 49 states to Ronald Reagan.

Polls show that the 2012 race should be close, but Romney is running far behind among Hispanic voters, the nation’s fastest-growing demographic. He could turn to Florida Sen. Marco Rubio or Nevada Gov. Brian Sandoval to try to change that, but obvious pandering is poor politics, and Sandoval especially is, arguably, inexperienced on the national stage.

5. A nominee’s selection of a running mate reveals how he would govern.

Actually, it’s more about politics than governance. As recently as 1920, when convention delegates ignored Warren Harding’s choice of a running mate and selected Calvin Coolidge instead, presidential nominees had very little to say about who their running mates would be.

But in recent decades, presidential nominees have become increasingly engaged in the vetting and selection process because none of them want a repeat of the debacle of 1972, when George McGovern had to drop Thomas Eagleton from the ticket after revelations that Eagleton had undergone electroshock therapy.

Even if not prophetic, the choice says something about the presidential nominee. The Palin pick underscored McCain’s impulsive streak, while Biden suggests Obama was aware of his inexperience.

Romney’s choice will reveal something about his nature, too, though, if history is any guide, it will say more about what he thinks he needs to do to win the election than how he would govern the nation. Despite all the vetting, the key question — will the running mate be up to the rigors and scrutiny of a national campaign? — can’t be answered until after the selection.