What exactly does a U.S. vice-president do? It would have shocked the country's founders

They'd have been bewildered, back in Daniel Webster's day, by this week's blanket news coverage and tea-leaf-reading dedicated to the choice of a U.S. vice-presidential candidate.

The vice-presidency was maligned and ridiculed in that bygone era whenstatesmen sported mutton-chop sideburns andsat stone-faced in black-and-white photo portraits.

Webster was offered the position and turned it down.

"I do not propose to be buried until I am dead," he replied, saidJoel Goldstein, a scholar on the vice-presidency.

Like many of his generation, the 19th-century statesman viewed the vice-presidency as so pointless, so soul-crushingly devoid of purpose, that he said thanks, but no thanks.

That was a common view throughout U.S. history.

Holders of the post mocked it with self-deprecating one-liners long before the TV show Veep practically turned disparagement of the office into its own comedic genre.

But the position has changedand grown over time, illustrating a broader evolution in U.S. politics in which the presidency has gained, and Congress has lost, political power.

Joe Biden told a story this week that underscored that change.

As he introduced his running mate, Kamala Harris, the presumptive Democratic nominee described what happened when Barack Obama offered him the same job in 2008.

"[Obama] asked me what I wanted most importantly. I told him I wanted to be the last person in the room before he made important decisions," Biden said.

"That's what I asked Kamala. I asked Kamala to be the last voice in the room. To always tell me the truth."

In other words, the VPis now a top adviser to the president. And a troubleshooter the lead on a few serious files, like a pandemic; a trusted envoywho flies on Air Force Twoto carry the president's message to foreign capitalsor rides a limousine motorcade up to Capitol Hill to represent the boss in a legislative negotiation.

Nearly one-third become president

Nearly one-third of the office's holders have gone on to become presidentthrough election or succession.

That's especially relevant this year given how historically old the election contenders are.

The chance of an average American male of Biden's age who might need to be, erm, replaced over the next four years stands at nearly one-in-five, according to actuarial science.

That's what happened in Webster's day.

The next president died a couple of years later, and the man who accepted the running-mate role in his stead, Millard Fillmore, wound up in the White House in 1850.

But the VP job occasionally went unfilled for years, until the 25th Amendmentwas ratified and became part of the U.S. Constitution in 1967, allowinga president to fill a vacancy.

From the founding to today

The country's founders had spent little time thinking about the office and originally gave the position to whomever finished second in the Electoral College vote.

"It was really an afterthought," Goldstein said in an interview.

"We don't know exactly why [the founders] created it."

The original system devolved into an awkward deadlock between political rivals and was changed a few years later.

In its next incarnation, the job was viewed as a patronage post and often went to people with no federal experience like a customs official, businessmenand state lawmakers.

It took numerous decades for presidents to start picking their own running mates, with party bosses controlling the process until then.

Dwight Eisenhower was caught off-guard when asked whom he wanted named as his running mate at the 1952 Republican convention.

"'I thought the convention had to do that,' [Eisenhower] replied, apparently unaware he had any say in the matter,"veteran political writer Jules Witcover recounts in his book, The American Vice Presidency.

"After briefly mentioning some other names, they agreed on [Richard] Nixon."

The role grew under Nixon. He began attending cabinet meetings and visited dozens of countries on Eisenhower's behalf. He was himself elected president after two tries.

The man who beat Nixon in his initialpresidential run John F. Kennedy was among the first to pick his own vice-president.

But he was shocked when Lyndon B. Johnson accepted.

Kennedy was desperate to win Texas and, at the 1960 convention, made a conciliatory offer to its native son. Kennedy friend and biographer Arthur Schlesinger Jr. said the president came back from LBJ's hotel room with startling news.

"You just won't believe it.... He wants it.... Now what do we do?" JFK told his brother, in an account originally included in Schlesinger's Robert Kennedy biography and repeated in Witcover's book.

The role grew over the 20th centuryas presidents themselves took on more power for instance, signing far more executive orders.

The big turning point

The final major turning point came after 1972.

At a sad and awkward news conference, Democratic nominee George McGovern announced that he was withdrawing his VP pick, who was standing right next to him.

This was after days of controversy following news that Sen. Thomas Eagleton had received electroshock therapy as treatment for depression.

Pressed by reporters, McGovern, who had originally hoped to recruit Edward Kennedy, said it had been a chaotic party convention and he hadn't properly vetted his choice.

"We didn't have the time and the deliberation that were needed. I was still writing my acceptance speech within two or three hours of the time I had to deliver it," McGovern replied.

The next Democratic nominee vowed not to repeat the mistake.

Scholars of the vice-presidency credit Jimmy Carter and his running mate, more than anyone, with modernizing the role.

Carter took the selection process seriously, choosing Walter Mondale from an original list of hundreds of namesafter interviewing the candidates.

The Georgia governor wanted a VP with Washington experience to compensate for his own lack of it, and he landed on the senior senator.

Goldstein said Carter also viewed reform as a moral issue. He considered it was wrong to leave a potential presidential replacement out of the loop and unprepared for the big job.

Nuclear bomb? What nuclear bomb?

The development of the nuclear bomb offers a classic, if chilling, example.

Harry Truman was kept in the dark about the Manhattan Project to build the bomb he only found out about it after Franklin Roosevelt died.

Carter let Mondale write a new job description for vice-president.

And that job description resembles the role we know today: VP as top adviser, present in key meetings, with access to intelligence briefings, playing a lead role on specific filesand guaranteed regular lunches with the president.

Carter not only agreed to those conditions; he even offered his running mate an office in the White House.

The1976 election was also the first featuring a televised vice-presidential debate.

Early in the Carter presidency, Mondale was sent on a world tour to meet with NATO and other allies, and a New York Times piece called the reinvention of the role a legacy of Carter's first 100 days in office.

"Because the perception was that [because] the vice-president mattered to the president, he mattered to other people," Goldstein said.

"The vice-president became part of the president's inner circle."

The current role

That pattern persisted. Under Bill Clinton, Al Gore took a lead on environmental, telecommunications and Russia issues.

Dick Cheney had tremendous power from the start, leading the presidential transitionand selecting key cabinet members for George W. Bush. He oversaw numerous policy areas. Most notoriously, he advocated for the Iraq War.

Biden was involved in the 2009 recovery bill, pandemic preparationand budget negotiations with congressional Republicans.

In an interview for Witcover's book, Biden said the president alone can't handle the increasing scope of issues that now cross the Oval Office desk.

"The president's plate is so very full," hesaid.

WATCH | Biden and Harris make first appearance as running mates:

Biden and Harris take on Trump in first appearance as running mates

4 years ago

Duration 2:47

California Sen. Kamala Harris and former Democratic rival turned presidential running mate Joe Biden appeared at their first joint campaign event in Delaware. After singing each other's praises they took political aim at U.S. President Donald Trump, who has already come out swinging at the Biden/Harris ticket.

As Biden conducted his search for a running mate, there were days, weeksand months of frenzied media speculation.

Reporters produced countless profiles of the potential running mates, unearthing unflattering material about the candidates, publishing gripes from rivals, even tracking flights to Biden's state of Delaware for clues. This week he offered the job to Harris, aCalifornia senator and ex-prosecutor.

And unlike Daniel Webster, she said yes.