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Joe Biden is zeroing in on a running mate selection, according to CNN’s latest reporting.

He’s particularly interested in picking a woman, and three of the four leading prospects are women of color.

I talked to Kate Andersen Brower, a CNN contributor and the author of “First in Line: Presidents, Vice Presidents, and the Pursuit of Power,” about how this pick is more important than most, how Biden will do it and how the process came to be.

She’s also written about presidential transitions and talked to us recently about what Trump will be like if he wins and if he loses.

But today it’s running mates. Our conversation, conducted via email and slightly edited, is below. She included excerpts from her book, for which she interviewed every living former vice president, in her replies.

How did this process come to be?

ZW: These days a major-party presidential candidate picks his or her running mate. But that’s not what the framers of the Constitution intended. Briefly, how did this process come to be?

KAB: It was not until 1940 that presidential candidates chose their own running mates.

When the Founding Fathers gathered in Philadelphia in 1787 to write the Constitution, the vice presidency was not at the center of their attention. Article I, Section 3, of the Constitution states that the vice president will preside over the Senate “but shall have no vote, unless they be equally divided.” The Founding Fathers, wary of anything resembling a monarchy, were concerned that a president may become too powerful if the vice president had any role in the Senate greater than serving as tiebreaker, so the vice president’s job description was kept deliberately diminutive.

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They created a system — the Electoral College — in which each state has a number of electors equal to the number of the state’s senators and members of the House of Representatives. But there was no differentiation between presidential and vice presidential candidates on the ballot, and each elector cast two votes for president (for different candidates, sometimes from different parties) and no vote for vice president.

The candidate who won the majority of electoral votes would become president and the runner-up would be named vice president. The House of Representatives would break a tie. As runner-up, the vice president was heir apparent to the presidency, which explains why John Adams and Thomas Jefferson were the nation’s first two vice presidents and its second and third presidents. And they were from two different political parties who were constantly jostling for power.

In 1804 the 12th Amendment was adopted, recognizing the reality of political parties and dictating that each elector cast separate votes for president and vice president. This significantly weakened the position, making the vice president a stand-in and not the second-most-qualified politician for the presidency.

In 1940, Franklin Delano Roosevelt changed everything. He only agreed to seek a third term as president if he could pick Henry Wallace as his running mate; his demand that party convention delegates go along with his decision changed the way vice presidents were chosen and gave the presidential candidate the ability to select his running mate.

So, in short, the Electoral College decided who the vice president would be until 1940.

What kind of running mate will Biden pick?

ZW: A candidate will often try to pick a running mate that helps round out their profile. Barack Obama, a relative newcomer in 2008, picked an old Washington hand. Donald Trump, an outsider and bomb thrower, picked Mike Pence, a staunch conservative. What does Joe Biden need to help round himself out?

KAB: The vice presidency in 2020 is more consequential than it has ever been before. We are in a moment when the Black Lives Matter movement and demands for racial equality are at the forefront of the public discourse. Biden would be wise to seize on that and choose a woman of color for balance. He is an older white man who seems well aware of the opportunity to name a woman like Sen. Harris or Rep. Demings and give them a real shot at succeeding him as president one day.

That is the single most important role of any vice president, the ability to step into the president’s shoes.

The vice president used to be a punchline, and you can watch an entire HBO series based on that premise! John Nance Garner, who was one of FDR’s VPs, famously said: “The vice presidency is not worth a bucket of warm piss [later cleaned up to “warm spit”].” Thomas R. Marshall, vice president under President Woodrow Wilson, said, “Once there were two brothers: One ran away to sea, the other was elected vice president. Nothing was ever heard from either of them again.”

You can be sure that Biden’s VP will not feel this way.

The vice presidency is most certainly not a joke anymore. Biden would be the oldest president (78 on Inauguration Day); voters will want to know that there is a capable person waiting in the wings to take over if his health should fail.

Biden’s stated decision to pick a woman is smart because the most energetic wing of the Democratic Party is the more diverse, liberal left. We have had almost four years of a homogenous White House with mostly white men in positions of power. Democrats will want to see a Cabinet and a vice president who is reflective of the party, so bringing in more women and people of color is key. Obama energized young voters, so Biden will want to choose a running mate who can get them to the polls.

Because he was VP for eight years, he knows exactly what he’s looking for. Biden will want someone who he has a close relationship with, as he did with President Obama. He admired Obama’s intellect and calm immensely. An aide who worked for Biden when he was vice president told me, “He was kind of a fanboy, honestly.” Biden is going to be looking for someone who is an admirer of his decades of service in Washington. Sen. Harris was very critical of Biden early on during the primary debates and that could be a factor.

A double standard for women as running mates

ZW: Let’s assume Biden picks a woman (a safe bet!) – she’d be the third woman to be a major-party running mate. Is the process somehow different for women?

KAB: It is incredibly unfair, but the process for women can be more complicated because typically they have husbands who have careers (before the 1950s and ’60s most of the spouses of vice presidential candidates, all of whom were women, did not work outside of the home).

So the key question for any female vice presidential candidate is even trickier: ‘Is there anything you would not want to see on the front page of The Washington Post?’ is the standard catchall when vetting candidates.

For women the question becomes, Is there anything any member of your family has done that you would not want to see on the front page of The Washington Post?

In the age of social media that means any Instagram posts, tweets, etc., posted by a candidate’s child or spouse. And that process for women carries that extra weight of their husband’s finances and career.

When Walter Mondale ran against Ronald Reagan in 1984, he knew he had to make a historic pick if he was to beat the wildly popular sitting president. Tom Bradley, the first African American mayor of Los Angeles, was on Mondale’s shortlist, along with Dianne Feinstein, then the mayor of San Francisco, and New York Rep. Geraldine Ferraro.

“We weren’t doing oppo [opposition research] on Tom Bradley’s wife,” Mondale’s campaign manager Joe Trippi explained to me — she was a private person who hosted teas and played the part of the supportive political wife, she was not in charge of a business.

“Therefore why would you be doing oppo on Geraldine Ferraro and Dianne Feinstein’s husbands?”

But after Mondale picked Ferraro, the first woman to ever be the running mate of a major presidential candidate, revelations surfaced about her husband’s business dealings that badly damaged the campaign.

“From that day forward it was proven that you have to go much further than looking at the person themselves,” Trippi said.

The process is evolving

KAB: As more women make it onto the list of vice presidential candidates, the mostly male, white-collar Washington and New York lawyers who do most of the vetting are aware they need to rethink their approach. Instead of asking a man if he’s ever sexually harassed anyone, now the question is tweaked and the woman being vetted is asked whether she has ever been sexually harassed.

One experienced vetting lawyer said that he prefers it when a female colleague sits in the room with him when he is asking such personal questions. Often the most shocking revelations come up in conversations rather than on written questionnaires, because no one wants a paper trail.

Do not procrastinate

KAB: Biden can learn from John McCain and not wait until the last minute to make his decision.

McCain was left scrambling for a running mate. Sarah Palin was not nationally known and had been governor of Alaska for less than two years. She was not even on McCain’s long list of potential candidates. She came to his attention because the other choices were too predictable and not the game changers he and his campaign strategists thought he needed in order to win.

McCain’s vetting lawyers had just 72 hours to vet Palin, who was 44 years old and just six years removed from being mayor of Wasilla, Alaska. It was one of the biggest gambles in modern politics. Biden, of course, has had much more time.

Be honest, be decisive

KAB: The potential running mates Biden is looking at can learn from Palin’s answer to this question, which was posed to her by a member of McCain’s team and showed her strength:

“You’re the acting president, the president just had surgery and the director of intelligence comes in and says they have a confirmed sighting of Bin Laden in the northwest territories of Afghanistan. He tells you that we have a plane overhead ready to take the shot, but there will be multiple civilian casualties. Do you take the shot?”

Palin replied, “Yes, I would take the shot because I’m the President of the United States, this is our archenemy who took the lives of three-thousand-plus Americans. And then I would get down on my knees and ask for forgiveness for the innocent souls whose lives I would be taking.” It is important for women to project strength.

They should also be honest from the start. It is always best to lay everything out on the table during the vetting process. Palin did not reveal the pregnancy of her 17-year-old daughter, Bristol, on the written questionnaire, but she told someone on McCain’s team during a phone conversation later.

Another thing to learn from McCain and Palin is to try and develop a personal relationship early on. McCain had spent less than three hours with her when he announced her as his running mate.

More harm than good?

ZW: Is there any evidence that a running mate actually helps a candidate or gives them a bump in the polls? Is there a running mate who has had a very bad effect on a candidate?

KAB: It’s a parlor game in Washington to opine on how different potential running mates can help secure votes from different demographics, but presidential candidates want something much simpler: They do not want to be embarrassed.

Two examples of running mates who hurt the candidates are Thomas Eagleton and Palin. In 1972, South Dakota Sen. George McGovern picked Missouri Sen. Thomas Eagleton as his running mate. At a time when mental health was even less understood than it is now, Eagleton was forced to leave the ticket after just 18 days when it was revealed that he suffered from depression and had undergone electroshock therapy.

A more recent example is Palin. Her personal issues and her lack of exposure to national media attention led to a caricature of her as an unsophisticated and inexperienced vice presidential candidate. Campaign aides understand that vice presidents cannot help their candidate get elected, but they can certainly hurt. Palin proved that to be true. Palin cost McCain 2.1 million votes, or 1.6 percentage points, according to a 2010 study by researchers at Stanford University.

What’s going on in the process right now?

ZW: How does this process actually work? What’s probably going on behind the scenes right now?

KAB: Biden knows this job inside and out since he was in it for eight years.

Biden and Obama agreed to five ground rules in a private written document:

“JRB and BO have weekly unstaffed meeting; JRB can sit in on any BO meeting; JRB must have contemporaneous receipt of all paper — All printed words that go to BO go to JRB; JRB staff must be included in any meeting with their parallel BO staff; JRB will not have a portfolio, because he will be involved in everything.”

One other thing, Biden told Obama: “I’m not changing my brand. I am what I am.”

Vetting lawyers often have less than a month to dig up everything they can possibly find on a potential running mate. Many of the questions they ask the finalists are cringeworthy. Rumors of infidelity or financial impropriety are often the tip of the iceberg, and sometimes the lawyers decide to call off a vet early if broader outreach will do nothing more than embarrass the person being vetted.

With less than a month to uncover every detail about a person’s life, and without the help of the FBI, the job of vetting is more private eye than white-collar attorney. Most people, no matter how much they say they do not want to be vice president, eagerly answer vetters’ questions.

But the digging goes far beyond interviews with candidates. Jim Hamilton, a well-respected Democratic lawyer who vetted running mates for John Kerry, Obama and Hillary Clinton, said there are four standards for vetting: thoroughness, confidentiality, expedition and respect. He recognizes that there is an inherent tension between them. Occasionally, he’ll tell his lawyers not to interview too many people, especially when they travel to the candidate’s hometown and track down their eighth-grade teacher. The more people who are interviewed, the more likely there’ll be a leak.

The list of questions is now well over a hundred.

Vetters collect everything that the candidate has ever written, they sit down with spouses, they ask for details of former relationships, they log into private social media accounts and they insist on tax returns. They even look at the potential nominee’s children’s, and in many cases grandchildren’s, Facebook pages and Instagram accounts. They want to know everything, even if it’s not disqualifying. In order to make sure embarrassing revelations do not see the light of day, anything that is written, including notes about what the candidate said during his or her interviews with the lawyers, is either destroyed or given back to the person being vetted.

“There are no written reports of the vets,” said Hamilton. “The reports are made to the nominee orally. I don’t want any written record.”

At the beginning of the vetting process lawyers put together a “black book” on each contender on the long list. The book is compiled from publicly available material and is part of what is referred to as a “blind vet,” because the people being vetted do not know they are under consideration.

The option Obama’s advisers wouldn’t give him

ZW: There’s a lot of secrecy and cloak and dagger stuff in the recent history of these selections. Why do campaigns want to hold this pick as a big reveal?

KAB: Obama’s vetting team initially focused on 23 people. Obama asked for the so-called black book on each of the candidates. Vetters flew to Obama’s Chicago campaign headquarters to present him with the books. But there were 22, not 23.

“I have 22 books for you,” a person who was involved in the process, but who spoke on the condition of anonymity, told Obama.

“But we agreed to 23,” Obama replied.

“Yes,” the person said, “and I decided not to bring the 23rd.”

“I wanted 23,” Obama, who is famously unemotional, said, sounding a bit annoyed.

“It would be very bad politics for you to have a book that had been prepared on one of the candidates,” the person told him, “because it’s got so much dirt in it.” The vetting lawyers were so concerned about this one person that they were worried about even putting a binder together on him, fearing it could be traced back to the Obama campaign. The information was too scandalous. Obama, of course, wanted to know who it was. The room was packed with campaign staff, so the person told Obama they should speak alone in the hallway.

“So, who didn’t you do a book on?” Obama asked.

“Mike Bloomberg.”

Obama nodded his head, but this time he kept his poker face and returned to the room. One New York Times article published on May 2, 2008, noted that more than 50 women were accusing Bloomberg L.P. of discriminating against pregnant employees.

There was no disputing it for Obama’s vetting team: Bloomberg was absolutely off the table. The three finalists were far less controversial: Joe Biden, Indiana Sen. Evan Bayh and Virginia Gov. Tim Kaine.

Being VP goes only so far

ZW: Biden’s the first former vice president to be on the ballot as a presidential candidate since Al Gore, who lost in 2000. George H.W. Bush was a former vice president who served only one term. 

KAB: Serving as VP certainly does not guarantee you the presidency. In fact, sometimes it makes it more difficult, because they must answer for the record of the person they worked for. In Gore’s case, he struggled to create his own identity while celebrating the administration’s successes and downplaying the scandals that consumed the Clinton White House. “You’re number two,” Gore told me in an interview, “and whether it’s in politics or business or other professions, you have to make a transition from being number two to number one.”

Gore pollster Stan Greenberg made the case that Gore should not run on the Clinton-Gore record and should distance himself from Clinton. Gore chose to follow Greenberg’s advice. They needed to capture the under-50 non-college-educated white women who questioned Gore’s morality because of his association with Clinton, Greenberg said.

Former Clinton aides maintain that not using Bill Clinton to campaign for him was the single biggest mistake Gore made.

The two men who had once been friends and partners met alone for a two-hour conversation after Gore lost the election, a meeting that was deliberately kept off their public schedules. The discussion was a political autopsy of what went wrong, and there was plenty of blame to go around. Clinton said he understood why Gore wanted to run on his own, but at the end of the day, Clinton argued, he could have been helpful in some key states, particularly his home state of Arkansas, which Gore lost by less than 5 percentage points.

In New Hampshire, Clinton said, George W. Bush won by a slim margin, and Clinton had approval ratings over 60% there. If he had gone there, Clinton argued, Gore would be president. “I think you made a mistake not to use me more in the last 10 days,” Clinton told him.

Could Trump dump Pence?

ZB: It hasn’t happened in a while, but there is a lot of precedent for presidents finding new running mates. (Richard Nixon and Abraham Lincoln, to name two.) Is it too late for Trump to reconsider Mike Pence?

KAB: Presidents are looking for someone to balance out their weaknesses, as Ronald Reagan did when he picked George H.W. Bush, who was perceived as more moderate.

Pence certainly lends Trump much needed credibility with Christian conservatives and he has proven his loyalty again and again. Ultimately, it’s a bad decision to dump the vice president, because you should stick with the one you walked in with.

Gerald Ford had always regretted replacing Nelson Rockefeller with Bob Dole.

“I was convinced with Reagan in the race, and given the makeup of the party, there wasn’t any way we could win the nomination unless we captured conservative votes,” Dick Cheney, who worked for Ford, said. “We would never get those conservative votes if the guy we had running with us on the ticket was Nelson Rockefeller.”

In the end, Ford deeply regretted dumping Rockefeller, in part because he lost and also because he felt guilty about the decision. Using Rockefeller’s nickname, Ford told friends that “Rocky took himself out,” but everyone knew he was forced out. “It was the biggest political mistake of my life,” Ford later confessed. “And it was one of the few cowardly things I did in my life.”

Melania was key to Trump’s pick

KAB: Even though she was conspicuously absent when her husband actually announced Indiana Gov. Mike Pence as his running mate, Melania Trump was a critical voice in the meeting with other family members where he settled on the pick.

It was the first time in modern campaign history that the wife of a presidential candidate was not at the public announcement, and it was an early indication of how uncomfortable she would be as first lady.

It was decided at that final meeting that what they needed was someone with “safe hands,” as vetting lawyers call it. Someone who would be calm in a crisis; someone who could instill a sense of confidence in the Republican base that remained deeply skeptical of Trump. Most of all, what they needed was someone who could take over the presidency, if necessary.

Melania was keenly aware of the need to balance her husband, who has spent much of his public life — and most of his life was lived clinging to the spotlight— awash in scandal. She wanted to make sure that there were absolutely no skeletons in his running mate’s closet. But one finalist had a closet full of them (still, Donald Jr. backed him until the end), and another contender was so controversial that he would be ousted within the first few weeks of the administration when he served in a different position. Melania’s shrewd instincts proved correct; Mike Pence was by far the least controversial on Trump’s list of vice presidential candidates, and Pence could help Trump win over conservative Republicans.

Pence’s ‘divine appointment’

KAB: Trump was also looking for someone who fit the part, someone who looked like a vice president. “Straight from central casting,” Trump is reported to have said of Pence.

In the end, it was down to two men. Pence, a devout evangelical Christian in his late 50s, won out over former Speaker of the House Newt Gingrich, the much more controversial finalist, who, like Trump, was in his 70s and had been married three times.

One longtime friend of Pence’s said that Pence considered the vice presidency his “divine appointment.”

There was no specific agreement reached between Pence and Trump about what Pence’s role would be as vice president, but in the end there was very little hesitation on the part of both Mike and Karen Pence.

“They felt called to do this,” Jim Atterholt, who was Pence’s chief of staff when he was governor of Indiana, recalled in an interview with me. “They knew what they were getting into, they knew the history, they knew the challenges, and they accepted that as part of their calling.”

There is no one who can hold the Christian conservative base like Mike Pence.