Biden drops out of 2024 presidential race, endorses Kamala Harris

President Joe Biden is dropping out of the 2024 presidential race and endorsing Vice President Kamala Harris as his replacement, he said Sunday. 

The 81-year-old commander in chief announced his exit in a letter posted to social media. His decision follows a lackluster debate performance that kicked off a growing number of calls from fellow Democrats to withdraw. Biden also tested positive for COVID-19 this week. 

The decision marks a swift and stunning end to Biden’s 52 years in electoral politics, as donors, lawmakers and even aides expressed to him their doubts that he could convince voters he could plausibly handle the job for another four years.

The latest: 

Staff found out minutes before announcement

Senior campaign and White House staff were notified just minutes before the letter went out, people familiar with the matter told The Associated Press. 

Biden had been reflecting on his future for the past couple days and the decision was closely held.

Kamala Harris responds 

Vice President Kamala Harris – now the frontrunner for the 2024 Democratic presidential nomination – has responded to Biden's announcement and subsequent endorsement of her as the nominee. 

Here's her statement in full: 

"On behalf of the American people, I thank Joe Biden for his extraordinary leadership as President of the United States and for his decades of service to our country. His remarkable legacy of accomplishment is unmatched in modern American history, surpassing the legacy of many Presidents who have served two terms in office.

It is a profound honor to serve as his Vice President, and I am deeply grateful to the President, Dr. Biden, and the entire Biden family. I first came to know President Biden through his son Beau. We were friends from our days working together as Attorneys General of our home states. As we worked together, Beau would tell me stories about his Dad. The kind of father — and the kind of man — he was. And the qualities Beau revered in his father are the same qualities, the same values, I have seen every single day in Joe’s leadership as President: His honesty and integrity. His big heart and commitment to his faith and his family. And his love of our country and the American people.

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."I am honored to have the President’s endorsement and my intention is to earn and win this nomination. Over the past year, I have traveled across the country, talking with Americans about the clear choice in this momentous election. And that is what I will continue to do in the days and weeks ahead. I will do everything in my power to unite the Democratic Party — and unite our nation — to defeat Donald Trump and his extreme Project 2025 agenda."We have 107 days until Election Day. Together, we will fight. And together, we will win."

GOP calls on Biden to resign

GOP leaders are calling for Biden to resign.

"If Joe Biden is not fit to run for President, he is not fit to serve as President. He must resign the office immediately. November 5 cannot arrive soon enough," House Speaker Mike Johnson said in a statement.

"If the Democratic party has deemed Joe Biden unfit to run for reelection, he’s certainly unfit to control our nuclear codes. Biden must step down from office immediately," tweeted Rep. Tom Emmer, R-Minn.

Trump responds to Biden dropping out 

Former President Donald Trump, the 2024 GOP presidential nominee, responded Sunday to Biden's decision to end his reelection bid. 

Trump responded to the news in a post on his own Truth social media site. 

"Crooked Joe Biden was not fit to run for President, and is certainly not fit to serve - And never was! He only attained the position of President by lies, Fake News, and not leaving his Basement. All those around him, including his Doctor and the Media, knew that he wasn’t capable of being President, and he wasn’t - And now, look what he’s done to our Country," the statement from Trump read, in part. 

Praise from Democrats, meanwhile, poured in for Biden.

READ MORE: Biden exiting race sparks massive reaction among politicians, experts and celebs

Biden endorses Kamala Harris

In a separate post on X (formerly Twitter), Biden endorsed Vice President Kamala Harris as the nominee.  Biden's endorsement of Harris makes her the frontrunner for the nomination, but that doesn't mean she can swap in for him at the top of the ticket by default. 

RELATED: Majority of Democrats think Kamala Harris would make a good president: poll

In a recent ABC News-Washington Post poll, Harris performed favorably in a theoretical matchup with Donald Trump, with 49% supporting Harris compared to 46% backing Trump. 

What Biden said

"It's been the greatest honor of my life to serve as your President," Biden said in the letter. "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."

"Democrats — it’s time to come together and beat Trump. Let’s do this," Biden said.  

He also said he will address the nation later this week to discuss his decision not to run. 

"I believe today what I always have: that there is nothing America can't do – when we do it together. We just have to remember we are the United States of America," Biden said in the letter. 

Biden will remain in office until the end of his term, which ends at noon on Jan. 20, 2025. 

What comes next?

Democrats are set to hold their convention in Chicago on Aug. 19-22. With Biden stepping aside, Democrats technically start with an open convention. But realistically, his endorsement pushes Democrats into murky territory. What was supposed to be a coronation for Biden now becomes an open contest in which nearly 4,700 delegates will be responsible for picking a new standard-bearer. 

The path ahead is neither easy nor obvious, even with Biden endorsing Harris. There are unanswered questions about logistics, money and political fallout.

Biden won every state primary and caucus earlier this year and only lost the territory of American Samoa. At least 3,896 delegates had been pledged to support him.

Current party rules do not permit Biden to pass them to another candidate. Politically, though, his endorsement is likely to be influential.

The immediate burden is on Harris to solidify support across almost 4,000 delegates from the states, territories and District of Columbia, plus more than 700 so-called superdelegates that include party leaders, certain elected officials and former presidents and vice presidents.

Who else could replace Biden?

Even before Biden announced his decision, Democrats floated other names as potential presidential contenders. 

In addition to Harris, others that endorsed Biden in 2024 while having their own presidential aspirations for future election cycles include California Gov. Gavin Newsom, Michigan Gov. Gretchen Whitmer, Pennsylvania Gov. Josh Shapiro, Illinois Gov. J. B. Pritzker and California Rep. Ro Khanna.

Moreover, other candidates who Biden defeated during the party’s 2020 presidential primary could try again, including Sens. Bernie Sanders of Vermont, Elizabeth Warren of Massachusetts and Amy Klobuchar of Minnesota, as well as Transportation Secretary Pete Buttigieg.

Some Democrats argued publicly, and many privately, that it would be a no-brainer to elevate the first woman, first Black woman and first person of south Asian descent to hold national office. But fair or not, Harris also has not been viewed as an especially beloved or empowered vice president. 

Observers say the best scenario for her and Democrats is to quickly shore up support and project a united front. 

The Associated Press and Daniel Miller contributed to this report.