Aaron J. Thornton; Elijah Nouvelage / Bloomberg / Getty; Shutterstock / The Atlantic

If Joe Biden wins in November, his running mate could become the most consequential vice president in modern American history. The woman Biden picks could be seen as a potential president-in-waiting, a signal for the Democratic Party’s agenda in the years to come, and perhaps the most significant player trying to help Biden manage a country—and a federal government—in crisis.

Under normal conditions, the presidency and its manifold obligations are already too much for one person to handle. As Barack Obama’s vice president, Biden redefined the office by assuming a level of responsibility that his predecessors never had. If elected, Biden would likely follow a similar model, and potentially expand the authority of a constitutionally insignificant office beyond precedent.

Those responsibilities will be even more weighty as the country combats the coronavirus pandemic; endures the worst economic crisis since the Great Depression; and reckons with questions of race, policing, and discrimination reignited by the killing of George Floyd in Minneapolis. “Joe Biden’s vice president will most likely be the most powerful vice president in history because the trend is toward more powerful vice presidents, Joe Biden knows the value of having a vice president with lots of responsibility, and Joe Biden is going to inherit an epic disaster,” Dan Pfeiffer, a former Obama senior adviser and co-host of Pod Save America, told me.

At the same time, with Biden planning to serve as a “transition candidate” for a new wave of younger and more racially diverse Democratic politicians, she’s also likely to face a degree of attention and scrutiny that few vice presidents ever have. The task for Biden come January would be to maintain a healthy partnership with his vice president—without worrying that she’ll outshine him.

“History tells us that consequential presidents and vice presidents come out at times where they’re tested and tried, and I can’t imagine a period of time where the president and vice president are going to be tested more than in January 2021,” Michael Feldman, a senior adviser to former Vice President Al Gore, told me. “There’s just no chance that the person who he picks is not a consequential vice president or consequential historical figure. They just will be.”

For most of American history, the vice presidency was an insignificant office famously described as a “bucket of warm piss” and as “useful as a cow’s fifth teat” (or “a fate worse than death,” according to the HBO comedy Veep). That changed in 1976, when Walter Mondale accepted Jimmy Carter’s VP offer and laid out a vision for how the vice president could play a more intimate and active role in White House politics. Mondale, who would be leaving a safe Senate seat and a position on a select committee conducting one of Congress’s first major oversight investigations of the intelligence community, made clear to Carter that he wanted real authority, and he didn’t want to be bound to a singular policy area.

“The one thing that was not always true was that the vice president had power—it was only to the extent that the president allowed it,” Mondale told me. “I was able to help a lot because Carter had not been in Washington … and I had quite a bit of experience there.”

Carter agreed to Mondale’s terms. He integrated Mondale’s staff with his own, gave him an office in the West Wing, set up weekly lunches for the two to discuss the president’s agenda, included Mondale in the flow of national-security paperwork, and assigned him to be his chief troubleshooter to manage relationships on Capitol Hill, in state governments, and with labor unions. “Mondale didn’t want to be in charge of any specific program or department, because he thought that would be infringing on somebody else’s turf,” Richard Moe, Mondale’s chief of staff and a former Carter senior staffer, told me. “He wanted to be a general adviser and to take specific assignments when required.”

To this day, vice presidents have kept their White House offices and weekly lunches (though Donald Trump and Mike Pence’s are no longer one-on-one), and successive administrations have expanded the Carter-Mondale model of power-sharing. Gore, for example, championed environmental reforms and the “information superhighway,” an effort to expand the internet’s reach. Dick Cheney wielded tremendous influence on national security and the War on Terror.

But Biden’s vice presidency was the biggest leap forward from the Carter-Mondale model yet. Unlike previous veeps, Biden sustained a high level of influence with the president throughout their two terms in office, Joel Goldstein, a vice-presidential scholar at St. Louis University, told me. As Goldstein has previously written, much of that prestige was derived from Biden’s public loyalty to Obama, which he accomplished “without surrendering his public identity and becoming lost in the president’s shadow.”

“It was a natural role for Biden because it involved a lot of dealing with governors and mayors and legislators, and Biden likes that,” Goldstein told me. “He was good at it.”

In addition to his weekly lunches with Obama, Biden’s schedule was packed with time with the president, in keeping with his request to be the “last man in the room.” On any given day, Biden would start the morning by joining Obama for the Presidential Daily Briefing in the Oval Office after making the crosstown drive from the Naval Observatory. He might have additional meetings in the Oval Office with Obama and a Cabinet secretary, or a Situation Room briefing with intelligence-agency heads. Depending on the day, he’d head out of town for an address, a tour, or a foreign visit, or stay in Washington for meetings with legislators.

While previous vice presidents did wield authority over special projects, they weren’t in charge of the defining issues for an administration, such as Biden’s role in implementing the Recovery Act after the Great Recession and leading efforts to whip Republican support to pass the Affordable Care Act. Biden also received major foreign-policy assignments throughout both terms, including his role as a chief adviser and surrogate as the administration debated its Afghanistan policy in 2009.

Obama has credited Biden’s influence in policy discussions before, telling The New Yorker that “there were times where Joe would ask questions, essentially on my behalf, to give me decision-making space, to help stir up a vigorous debate.” And, as far as is publicly known, he never lost the president’s trust, unlike Cheney, who was iced out after Bush’s reelection, or Gore, whose presidential ambitions strained his ties with Bill Clinton. Biden has already signaled that he hopes for a similarly close relationship with his vice president, saying he’ll pick a “simpatico” partner.

Reflecting on Biden’s broad portfolio as vice president, Pfeiffer told me that “one reason he had so many projects is because of what we inherited.” If Biden and his running mate win in November, he’ll “yearn for the good ole days of the 2009 financial crisis."

The former campaign advisers and administration officials I spoke with said that in selecting his vice president, Biden should be thinking well beyond the campaign itself and focus instead on which person would best help him run the FDR-size presidency he’s alluded to building.

Just as it’s easy to imagine what the dynamic between them could be like, it’s possible to anticipate what kinds of responsibilities she’ll have. An Elizabeth Warren vice presidency, for example, could see her playing a major role in the economic recovery and implementing bankruptcy reforms that Biden adopted from her campaign platform. Michelle Lujan Grisham, the governor of New Mexico and the only Latina known to be still in the running, has been praised for her handling of the state’s coronavirus outbreak and could help Biden manage the federal response. Rising stars like Keisha Lance Bottoms, the reformist Atlanta mayor, and Val Demings, the police chief turned Florida congresswoman, could lead on criminal-justice reform. Kamala Harris, the apparent favorite to win the veepstakes, could do the same, while serving as a key congressional liaison.

What is almost certain about Biden’s pick is that, if he’s elected, she will be seen as the heir apparent, whether Biden is a one-term president or she runs in her own right eight years later, the longtime Republican strategist Charlie Black told me. “Whoever he picks is going to have even more scrutiny and testing than a normal VP nominee does,” Black said, “because of all the speculation there will be that they’re going to be the front-runner to be the president in four years.” That’s perhaps especially true if he picks a Latina or Black woman, positioning her to run as the face of a new, younger, and more diverse Democratic Party, and signaling to Black and Latino voters that their party cares about representation at the top of the ticket.

Biden has been careful on the question of whether he’ll seek a second term as president. But if he does forgo reelection, his vice president could establish another VP milestone by launching a presidential campaign in the middle of the first term, while still performing whatever duties Biden deputizes to her—something modern vice presidents have never done.

Launching a campaign so soon would mean she’d assume a level of influence over Democratic politics that vice presidents don’t usually have. In carving out an agenda for her own administration by about 2022, she’d set up a preview of what the Democratic Party could look like through the rest of the 2020s. If that agenda is more progressive, it could help energize the younger, more diverse voters the Democratic Party needs, attracting goodwill not only to her campaign, but to Biden too.

Still, the perception of Biden’s deputy as his successor could also challenge their relationship, regardless of how many terms he serves. If her vision of the Democratic Party meaningfully conflicts with Biden’s, it could create real or imagined tension between them. As my colleague Edward-Isaac Dovere recently wrote, Biden “wants to win, but he wants the win to be about him, not his running mate.”

She’ll have to spend time defining herself as a governing partner while fending off speculation about any conflicts in the West Wing, especially if the press begins to overanalyze her larger political ambitions, Jennifer Palmieri, the former communications director for the White House and Hillary Clinton’s 2016 campaign, told me. If she does her job well, she may be accused of trying to be too independent. If she tries to keep a low profile, she’ll be criticized for not having ambition.

Plus, she would be the first female vice president in history—a completely new experience for the country, on top of the fresh challenges of the pandemic, the economic crisis, and civil unrest. “It will be new and different because it’s a woman, but it is not going to be an easy relationship for either of them to balance, because of all the expectations and intrigue that will surround her,” Palmieri said. “Singular positions of power are subject to a lot of scrutiny and conflicting standards. So God love her. I think it’s going to be—it will be a lot.”

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