Joe Biden’s senior White House and campaign staff spent the past week insisting that the president planned to stay in the 2024 race despite mounting calls within the Democratic Party for him to step aside. As recently as Saturday, his aides were preparing a campaign schedule for his return to the White House next week. He had been recovering from COVID-19 at his beach house in Delaware, insisting he was still running but growing increasingly frustrated as a coordinated effort by some Democrats to pressure him to exit became public.

By Sunday morning, the president had changed his mind, according to sources who spoke on condition of anonymity. On Saturday evening, Biden began to consider whether he should withdraw, one of the toughest decisions of his 50-year political career. He consulted a small circle of aides, including Steve Richetti, one of his closest advisers; Mike Donilon, his chief strategist; Annie Tomasini, his deputy chief of staff; and Anthony Bernal, the chief of staff to First Lady Jill Biden.

Richetti, a longtime aide, drove to the president’s beach house on Friday. Donilon joined on Saturday. Together, they reviewed new polling data and discussed whether Biden could defeat Donald Trump in the current political landscape. Faced with the new data and anticipating another week of public defections within the party, Biden had a decision to make. He worked with Donilon to draft the historic statement announcing his withdrawal while Richetti handled the logistics of the announcement and informed other staff.

Biden made the final decision to drop out on Sunday morning, calling chief of staff Jeff Zients, campaign chair Jen O’Malley Dillon, and Vice-President Kamala Harris to inform them, sources said. On Sunday afternoon at 13:45 EDT (17:45 GMT), the president held a video call with his senior White House and campaign staff, including Anita Dunn, who manages his White House communications strategy. One minute later, he released a public statement that sent shockwaves across the American political landscape and upended the 2024 election.

“He said he had been reflecting on it over the past couple of days,” a senior White House official told the BBC. “It was a closely-held decision.” Though Biden did not mention Harris in his initial statement, he tweeted his endorsement for his vice-president about half an hour later. The two spoke multiple times throughout the day leading up to the announcement, according to sources familiar with the conversations.

First Lady Jill Biden, the president’s closest adviser, said in a statement that she supported his decision. “Down to the last hours of the decision only he could make, she was supportive of whatever road he chose,” said Elizabeth Alexander, the first lady’s communications director. “She’s his biggest believer, champion, and always on his side, in that trusted way only a spouse of almost 50 years can be.”

Many in the White House and the campaign were not informed of Biden’s plans in advance. Most learned about it from his social media post. Zients, the president’s chief-of-staff, held a call with White House officials and emailed the wider West Wing staff to confirm the announcement and thank them for their hard work. He also led a call with the president’s cabinet secretaries. Biden, meanwhile, spoke to several congressional Democrats, governors, and supporters, according to a White House statement. He planned to continue making calls on Sunday night and Monday.

Kamala Harris, who said she planned to “earn and win” the presidential nomination, spent Sunday afternoon calling lawmakers, including House Minority Leader Hakeem Jeffries, key party officials, and governors to shore up support for her candidacy. Though she has already earned the support of the president and top Democrats, her ascension to the top of the ticket will not be certain until delegates vote to confirm Biden’s replacement at the Democratic National Convention in August. Notably, former president Barack Obama has not explicitly endorsed her, while Bill and Hillary Clinton have.

During a campaign call on Sunday afternoon, as many were still digesting the news, top officials said the team would be “full steam ahead” behind the vice-president. “All of you, all of us, wherever we come from, are here for Joe Biden and Kamala Harris and to defeat Donald Trump. And while today is a big day of transition, nothing changes with why you got here and what we’re all here to do,” said Jen O’Malley Dillon, the campaign chair, according to a source familiar with the call. “But the path forward is a path that is for all of us to do this together.”