President Joe Biden dropped out of the 2024 race for the White House on Sunday, ending his bid for re-election following a disastrous debate with Donald Trump that raised doubts about his fitness for office just four months before the election.

The decision comes after escalating pressure from Biden’s Democratic allies to step aside following the June 27 debate, in which the 81–year–old president trailed off and often gave nonsensical answers. Biden endorsed Vice President Kamala Harris to take on Trump, and encouraged his party to united behind her.

Biden plans to serve out the remainder of his term in office, which ends at noon ET on Jan. 20, 2025.

“It has been the greatest honor of my life to serve as your President. And while it has been my intention to seek reelection, I believe it is in the best interest of my party and the country for me to stand down and to focus solely on fulfilling my duties as President for the remainder of my term,” Biden wrote in a letter posted to his X account.

Nearly 30 minutes later, Biden throw his support behind Harris, the party’s instant favorite for the nomination at its August convention in Chicago.

“Today I want to offer my full support and endorsement for Kamala to be the nominee of our party this year,” he said in another post on X. “Democrats — it’s time to come together and beat Trump.”

Biden’s decision came as he has been isolating at his Delaware beach house after being diagnosed with COVID–19 last week, huddling with a shrinking circle of close confidants and family members about his political future. Biden said he would address the nation later this week to provide “detail” about his decision.

Senior campaign and White House staff were notified just minutes before the letter went out, according to people familiar with the matter. Biden had been reflecting on his future for the past couple days and the decision was closely held.

The White House confirmed the authenticity of the letter.