Biden’s running mate is two decades younger than he is; the potential vice presidency seems like merely a first step.

For Joe Biden is elected in November, his presidency will likely be defined by history-shaping decisions made after long, deliberative, some might say operatic processes. Biden’s selection of Senator Kamala Harris of California as his running mate—the first woman of color to appear on a major-party ticket—was precisely that sort of careful, drawn-out decision.

Neera Tanden, the president of the Center for American Progress, says that Biden’s selection of a Black woman with Indian and Jamaican parents shows that Biden is running a very different campaign than Donald Trump. “In the selection of a vice president, he’s created a deep contrast between the pettiest of men and a man who obviously has no pettiness within him,” Tanden told me, minutes after Harris was announced.

The pandemic continues to upend every milestone of this election. If the Democratic National Convention hadn’t been delayed, Biden would have revealed his running mate much earlier in the summer. Instead, the 2020 “veepstakes” portrayed Biden as a candidate who takes especially long to make up his mind—then stretches out the process a little longer. Biden has effectively been the Democratic nominee for five months. In that time, countless vice-presidential potentials emerged, and most faded. Biden made it clear in March that he was committed to running alongside a woman. An early candidate was Senator Amy Klobuchar of Minnesota, who officially took herself out of the running after her prosecutor days came under attack after the murder of George Floyd.

“Glad to finally have the veepstakes drama behind us and start beating on Trump instead of each other,” one relieved top Democratic donor texted me after the Biden campaign’s announcement this afternoon.

Read: Kamala Harris’s very open secret

Unlike news out of the Trump White House and the Trump 2020 campaign, very little of Biden’s running-mate selection process leaked to the press, despite the efforts of reporters and activists with grievances, both sincere and performative. An unmistakable aspect of Biden’s campaign and one he will likely carry with him to the White House is his small, stable circle of aides who have been with him for years and are intensely loyal to him. He is able to talk out his thoughts with them—he likes to talk out his thoughts a lot, and at length—while feeling secure that they won’t turn on him. That won’t be so easy to keep up if he is president, and is forced to expand his top staff from the same “graybeards,” as younger aides sometimes refer to Biden’s confidants.

Throughout the vetting process, Biden considered running mates who had supported his campaign early on—such as Atlanta Mayor Keisha Lance Bottoms—and those who had tried to connect with him on a personal level, including Michigan Governor Gretchen Whitmer and Representative Karen Bass of California, according to people who’ve spoken with him along the way. Harris and Biden have been friendly for years, and Harris was close with Biden’s late son, Beau.

Because the pandemic has limited in-person campaigning, Harris’s most important job will be debating Vice President Mike Pence this fall. Harris gained national popularity after her intense questioning of various Trump nominees, including Brett Kavanaugh and Jeff Sessions, during their Senate confirmation hearings. Observers believe she will be an intense opponent for the more subdued Pence.

She’s also likely to bring big money to Biden’s campaign. “She has a proven track record as an incredibly strong fundraiser,” says Andrew Weinstein, a Florida-based member of Biden’s national finance committee. “Her announcement will certainly make a big splash with a lot of Democratic donors.”

By picking Harris over Susan Rice—whose time as United Nations ambassador and national security adviser to Barack Obama gave her a breadth of foreign-policy experience—Biden is hinting that he would want to take the lead as president in reaching out to heads of government around the world, which aides and advisers say will be a major focus if he beats Trump. Reentering the Iran deal and the Paris Agreement would be early goals, as would re-establishing America’s role as an internationalist force and a moral leader. Biden has bragged on the trail about knowing almost every foreign leader.

Having spent four years as a senator, Harris would enter the administration with relationships on Capitol Hill. But if Biden had been looking for someone to take the lead as a congressional negotiator, he might have gone with Bass, the Congressional Black Caucus chair, and a close ally of House Speaker Nancy Pelosi. Another central part of Biden’s campaign pitch is his long relationships with Democratic and Republican lawmakers alike. Picking Harris suggests that he’s looking to retain the primary role in congressional relations, too.

Since the early days of coronavirus-related shutdowns, Biden has talked about how Americans’ “blinders have been taken off” about what is wrong with the economy and Trump’s leadership. Among progressives, Biden’s talk of systemic issues has elevated hopes that he might be open to the more revolutionary thinking touted by Senator Bernie Sanders of Vermont. Had Biden chosen Bass or Senator Elizabeth Warren of Massachusetts, both of whom were more popular among progressives, he would have indicated a shift in that direction.

“Kamala Harris ran in the progressive lane and was able to nicely balance the progressive approach with a history of pragmatism, and that balance is exactly where Biden wants to be: He wants to dream big, but get things accomplished,” says Scott Mulhauser, a longtime Democratic aide who was the deputy chief of staff to Biden during Obama’s 2012 reelection campaign. “As someone who has mastered pushing the Senate as far as she could, he wants her as a partner to drive big agendas and to know when to cut the deal to get almost everything you want and actually get it done.”

Biden “doesn’t care about Twitter fodder. He’s always genuinely loved Kamala Harris, has always respected her abilities,” says Eric Ortner, a donor, and friend. “They care about saving America, protecting the rule of law, and uniting the country when our very health, lives, and existence is at stake.”

Back at the beginning of March, in what turned out to be the final rally of his campaign, in a high-school gym in Detroit, Biden looked over at Harris, Whitmer, and Senator Cory Booker of New Jersey and said, “Look, I view myself as a bridge, not as anything else,” adding: “There’s an entire generation of leaders you saw stand behind me. They are the future of this country.”

Tanden told me that Biden landed on “a vice president who can be a partner across the board.” Biden will turn 78 two weeks after Election Day. If he wins, he will be the oldest president ever inaugurated. Harris, 55, is now the odds-on favorite to be the Democratic nominee after Biden, whether that’s in 2024 or 2028.

Edward-Isaac Dovere is a staff writer at The Atlantic.