President Joe Biden announced Sunday he is dropping his bid to seek reelection, in a move upending the presidential race just four months before Election Day. In a letter posted Sunday, Biden wrote he was stepping aside “in the best interest of my party and the country.”

Biden endorsed his vice president, Kamala Harris, who quickly received the backing of many powerful Democrats but could still face a challenge for the party’s nomination. If elected, Harris would become the first woman to serve as U.S. president. She made history in 2020 when she became the first Black person, first person of South Asian descent and first woman to be elected vice president.

The 81-year-old Biden faced tremendous pressure to drop out following a disastrous debate with Donald Trump that raised questions about his physical and mental health, as well as his ability to beat Trump. Biden announced the decision while at his beach home in Delaware, where he has been isolating after testing positive for COVID.

Biden’s decision makes Trump, who is 78, the oldest presidential nominee in U.S. history.

Questions about Biden’s candidacy have been growing since at least last year. The activist group RootsAction launched a campaign called Don’t Run Joe 20 months ago. During the primary season, more than a half-million voters chose “uncommitted” instead of Biden to protest his support for Israel’s war on Gaza.

Biden’s decision comes just four weeks before the Democratic National Convention begins in Chicago on August 19, though the DNC has considered holding a virtual roll call vote to lock in a nominee before the convention. The DNC rules committee will meet on Wednesday. The last open Democratic convention took place in 1968 in Chicago after Lyndon B. Johnson decided not to seek reelection.

On Sunday, Harris wrote, “I am honored to have the President’s endorsement and my intention is to earn and win this nomination.” Harris has already picked up endorsements from 32 senators, 153 representatives and 10 governors, as well as former President Bill Clinton and former Secretary of State Hillary Clinton. New York Democratic Congressmember Alexandria Ocasio-Cortez endorsed Harris, writing, “it is crucial that our party and country swiftly unite to defeat Donald Trump and the threat to American democracy.” AOC had warned against the effort to push Biden out, saying the demand was being driven by wealthy donors.

Meanwhile, former President Barack Obama and former House Speaker Nancy Pelosi have yet to make any endorsement. Neither has independent Senator Bernie Sanders, who praised Biden as “the most pro-working class president in modern American history.”
Many Republicans, including House Speaker Mike Johnson and vice-presidential nominee JD Vance, responded to Biden’s announcement by calling on him to immediately resign as president.