How Joe Biden’s Enduring Grief for His Son Helped Lead Him to Kamala Harris

This article is part of the The DC Brief, TIME’s politics newsletter. Sign up here to get stories like this sent to your inbox every weekday.

As Joe Biden was mulling his choice of a running mate, there may have been one important question in the back of his mind. Sure, the polling and focus groups were informative. He listened to his advisers’ research and they felt like their insights were instructive. He kept calling old friends to get their impressions. Biden had liked all of the women he considered, his advisers said, but in interviews they suggested one thing he might have been asking himself all along was this: What Would Beau Do?

Beau Biden, the former vice president’s late son, was at the fore this week when Biden selected Sen. Kamala Harris of California from the group of qualified and formidable women on his shortlist of V.P. picks. Perhaps just as important as her Howard University education and whip-smart political instincts was her time as a state Attorney General. Harris and Beau Biden overlapped for four years as their states’ top prosecutors, Harris running California and Biden running Delaware. That connection, for a Washington veteran who places personal relationships above almost any other trait, stuck with Biden, his advisers said.

“I first met Kamala through my son Beau,” Joe Biden said on Tuesday during the long-awaited announcement. “He had enormous respect for her and her work. I thought a lot about that as I made this decision. There is no one’s opinion I valued more than Beau’s and I’m proud to have Kamala standing with me on this campaign.”

Beau Biden’s death in 2015 rocked the Biden clan in ways that escape description. Biden, who was then the Vice President of the United States, was visibly destroyed by the loss. No stranger to grief, Joe Biden still found himself paralyzed and numb, as we reported in a cover story earlier this year on Biden’s resilience. Biden and others saw Beau as his political heir: There was talk about Beau making a run at the job that had eluded his father during two earlier White House runs. In 2013, Beau Biden had been diagnosed with brain cancer, although he believed it to be in remission and was preparing for a 2016 run for Governor as the man he called “Pop” plotted a third presidential campaign of his own. Ultimately, the cancer returned and showed no mercy.

Through all of this, the elder Biden had continued to hold out hope for his son’s future — and to lean on his son’s advice. Their shared love of politics was something that couldn’t be faked. Even Joe Biden’s memoir of Beau’s fight with cancer cites his son’s enduring piece of advice; in “Promise Me, Dad,” Joe Biden says his son made him pledge to stay in the fight for what’s right. In due course, though, Joe Biden recognized he was in no state emotionally to seek the nomination, and in 2015 President Barack Obama helped him exit the race he never formally joined during a joint Rose Garden appearance.

Which is why Beau’s character, in absentia, helped his father make the final decision on his next partner. Bolstered by Joe Biden’s unshaking confidence that personal relationships can trump political rivalries, Harris seemed to be the most logical choice. The presumptive Democratic nominee has a great deal of affinity for Harris, even though she arrived in the Senate just as Biden was packing his boxes to leave the White House. Harris’ broadside of Biden during the campaign’s first debate may have left a bad impression on some Biden advisers, but ultimately Biden came to see it as just politics.

As Biden prepared to inform Harris that her life was about to change, he sat down at a desk with a framed greeting card that was a gift from Biden’s own father. In it, Hagar the Horrible screams at the heavens, “Why me?” From the sky comes the you-can-do-it mantra that has kept Biden going in the wake of the deep loss of his own son: “Why not?” The thought of campaigning with one of his son’s pals sounded like it could be fun, a way to memorialize his chief political gut-checker. Harris now stands in Beau Biden’s shadow — and it’s one unlike any other in the Biden orbit.

Make sense of what matters in Washington. Sign up for the daily D.C. Brief newsletter.