A heartbeat away: the vice presidency has long been the butt of jokes, but the job is a lot more important than it used to be.

• Author: Smith, Patricia

When voters go to the polls on November 6, they won't just be electing a president. They'll also be putting another man "a heartbeat away" from the most powerful office on earth.

Though only 1 percent of Americans typically say that the bottom of the ticket influences their vote, vice presidential nominees can make a difference in close elections like the one shaping up between President Obama, a Democrat, and his Republican challenger, Mitt Romney.

Obama's running mate, Vice President Joe Biden, can charm voters but has a reputation for making political gaffes on the campaign trail. Before becoming vice president, Biden was a U.S. senator from Delaware for 36 years.

Wisconsin Congressman Paul Ryan, Romney's choice for vice president, is chairman of the House budget committee and considered an expert on budget issues. But some of Ryan's ideas--including his proposal to change Medicare, a health care entitlement program that many elderly Americans have depended on for decades--are quite controversial.

Four years ago, Republican John McCain's surprise selection of then-Alaska Governor Sarah Palin as his running mate played a role in his defeat by Obama, according to most election experts. One reason that vice presidential candidates get more scrutiny than ever by the media is that vice presidents no longer serve as powerless figureheads in presidential administrations.

"It's certainly a good deal more than just going to state funerals these days," says Lee Edwards, a presidential scholar at the Heritage Foundation.

The shift began during the presidency of Bill Clinton in the 1990s and continued under his successor, George W. Bush. By all accounts, Presidents Clinton and Bush gave Vice Presidents Al Gore and Dick Cheney more power and influence than any other vice presidents in American history.

The importance of the No. 2 spot today would astound the Founding Fathers. Aside from taking over for a president who dies or can no longer serve, the Constitution assigns the vice president responsibility for presiding over the Senate and breaking fie votes. Other than that, the job wasn't given much thought, says Stanley N. Katz, a constitutional historian at Princeton University.

But the vice president has always been first in line in terms of presidential succession, and many of these understudies have ended up stepping into the lead role.

Of the 47 vice presidents since 1789, 14 have become president. Nine got the job without being elected, when...