President Biden will abandon his reelection campaign, saying that it is in the “best interest” of both the nation and the Democratic Party. He will stay on through the remainder of his term, and tells fellow Democrats to support Vice President Harris for the nomination. 

Mr. Biden has been pressured for weeks by fellow Democrats, elected officials, and major party donors to abandon his campaign after a disastrous debate performance against President Trump.

Mr. Biden mentioned the vice president in his letter to the nation, and suggested in a separate social media post that she should take his place.

“Let me express my deepest gratitude to all those who have worked so hard to see me reelected,” Mr. Biden writes. “I want to thank Vice President Kamala Harris for being an extraordinary partner in all this work. And let me express my heartfelt appreciation to the American people for the faith and trust you have placed in me.”

In a separate post on X, Mr. Biden wrote that Ms. Harris should be the party standard-bearer in 2024. “My very first decision as the party nominee in 2020 was to pick Kamala Harris as my Vice President. And it’s been the best decision I’ve made. Today I want to offer my full support and endorsement for Kamala to be the nominee of our party this year,” he wrote.

Ms. Harris thanked the president later in the day Sunday, and announced officially she would run for the Democratic nomination. “With this selfless and patriotic act, President Biden is doing what he has done throughout his life of service: putting the American people and our country above everything else.,” Ms. Harris wrote. “I am honored to have the President’s endorsement and my intention is to earn and win this nomination.”

Mr. Biden’s age was always a concern since he first kicked off his presidential campaign in April 2019. At 78 years old in 2021, Mr. Biden entered office as the oldest president in American history, and was on track to leave the White House at the age of 86 had he won reelection. 

Long before the June 27 debate that put on display Mr. Biden’s frailties for more than 50 million in real-time, voters told pollsters repeatedly that the president should not run for reelection due to his advanced age. 

Despite Trump being just three years younger than Mr. Biden, voters did not feel his age would be a problem during his second four-year stint in the White House. Just 51 percent of voters in a recent poll said Mr. Trump was too old to serve. 

One New York Times–Siena College poll found that Trump was running away with the general election with just four months left in the race. Among all voters, Trump won 49 percent to Mr. Biden’s 43 percent, which was the best result for Trump in the history of the Times–Siena polling. 

Mr. Biden’s endorsement of Ms. Harris likely puts to rest any serious challenge to the vice president at the Chicago convention next month, given that nearly 4,000 delegates who will be voting for the nominee were hand-selected by Team Biden. 

Ms. Harris has the greatest chance of beating Trump of any Democrat, if polls are to be believed. Her vice presidential pick could be hugely consequential in that effort. 

A recent survey from Public Policy Polling found that Ms. Harris would close the gap with Trump in critical swing states if she were to choose the right running mate. In Pennsylvania, Ms. Harris would lead Trump and his running mate Senator Vance, 47 percent to 46 percent if she tapped the state’s governor, Josh Shapiro, as her vice presidential pick. 

Other names that have been floated for Ms. Harris include the Kentucky governor, Andy Beshear, who twice defied political gravity to win the governorship in a deep-red state while running as a liberal Democrat. The governor of North Carolina, Roy Cooper, who was elected in 2016 and reelected in 2020 the same day Trump won his state, has also been floated as a potential veep.