Biden, at 81 years old, was due to accept the party's nomination at its national convention in August.

It's a remarkable end to a career in politics that spanned half a century.

I know how to do this job.

I know how to get things done.

Here's a look back at Biden's biggest moments in the Senate and White House.

Take a measure of me and my heart.

If you still disagree, so be it.

That's democracy. That's America.

Throughout his political career, Biden forged a role representing middle-class Americans.

I grew up in Scranton, Pennsylvania, in Claymont, Delaware, among working-class people who built this country.

Biden represented Delaware for 36 years in the Senate.

As chairman of the Judiciary Committee, Biden presided over the contentious Supreme Court hearings for Clarence Thomas, who was accused of sexual harassment by law professor Anita Hill, which Thomas denied.

Biden was criticized by some Democrats for his handling of the allegation, and he later said he regretted how he handled the hearings.

I regret I couldn't come up with a way to get her the kind of hearing she deserved.

As chairman of various other committees, Biden had several signature accomplishments.

He helped pass a sweeping crime bill that was later viewed as having contributed to mass incarcerations.

As a senator, Biden was intimately involved in U.S. foreign policy, as a leading voice on conflicts ranging from Bosnia and Kosovo to Iraq.

I have supported all along the need to remove Saddam Hussein or his weapons.

It's easy to second-guess what we should have done on the way to this point.

Biden entered the 1988 race as one of the leading contenders for president.

That campaign quickly unraveled amid allegations that he plagiarized a speech, which he ultimately said was an oversight.

I've concluded that I will stop being a candidate for president of the United States.

Twenty years later, Biden joined the 2008 presidential race but stepped out after a poor showing in Iowa.

That summer, Barack Obama tapped Biden as his running mate, in large part because he needed a seasoned Washington politician who had foreign policy experience.

Yes, I accept your nomination to run and serve with Barack Obama, the next president of the United States of America.

As vice president, Biden's portfolio included some of the most complicated and politically fraught issues on the president's agenda.

Biden oversaw the implementation of the controversial economic stimulus bill that was designed to address the recession following the financial crisis of 2007 and 2008.

He also became an advocate for ending the war in Iraq, despite voting for the U.S. invasion in 2002.

We went to war with too few troops. We went to war unnecessarily.

Throughout his career, Biden prided himself on being able to reach across the aisle.

You've been a real friend. You've been a trusted partner.

Biden launched his third attempt to win the Democratic nomination in 2019.

We are in the battle for the soul of this nation.

During the campaign, a group of women alleged that Biden touched them in ways that made them feel uncomfortable.

To that, he responded, "I hear what they're saying. I understand it. And I'll be much more mindful. That's my responsibility."

Biden struggled early on in the race, but he turned the tide in his favor by winning overwhelming support from Black voters in the South Carolina primary.

We know Joe. But most importantly, Joe knows us.

Biden selected then-Senator Kamala Harris to be his running mate, making her the country's first woman, first Black person, and first of Indian descent to serve as vice president.

After the most competitive primary in history, the country received a resounding message that Joe was the person to lead us forward.

In 2020, Biden defeated Trump and became the oldest person to assume the presidency.

I, Joseph Robinette Biden Jr., do solemnly swear.

Taking office just two weeks after the January 6 attack on the U.S. Capitol, Biden cast his presidency as an attempt to unify the country after years of political polarization.

Politics doesn't have to be a raging fire destroying everything in its path.

At the start of his term, he focused on helping the country reemerge from the COVID-19 pandemic.

He signed a $1.9 trillion COVID relief plan into law that included direct payments to Americans and enhanced unemployment and child tax credits.

He also nominated and won confirmation of Justice Katonji Brown Jackson in 2022, making her the country's first Black woman to serve on the Supreme Court.

It has taken 232 years and 115 prior appointments for a Black woman to be selected to serve on the Supreme Court of the United States.

Biden also enacted a sweeping $1 trillion infrastructure law, a central component of his domestic policy agenda.

He also worked to cancel student loan debt.

My campaign for president, I made a commitment.

I made a commitment that would provide student debt relief. And I'm honoring that commitment today.

Following the Supreme Court's 2022 ruling that overturned Roe v. Wade, Biden's administration made efforts to protect abortion rights.

Early in his presidency, Biden made the controversial call to withdraw U.S. forces from Afghanistan.

The Taliban's swift takeover surprised Biden's administration and led to a tumultuous ending to America's longest war, leaving a mark on Biden's presidency.

His foreign policy record was also marked by the wars in Ukraine and Gaza.

Biden gained bipartisan support for taking a strong stance against Russia after its invasion of Ukraine, though he drew some criticism for not issuing sanctions sooner.

He pledged unwavering support for Israel.

But as the humanitarian crisis in Gaza worsened, he received backlash from Muslim and Arab American voters, as well as progressives.

Cease fire now.

He later pushed Israel to reduce the rate of civilian casualties in Gaza.

The conduct of the response in Gaza, in the Gaza Strip, has been over the top.

A swell of immigrants illegally crossing the border from Mexico presented another set of challenges for Biden.

Many voters came to believe the president wasn't aggressive enough in stopping illegal immigration.

Biden also dealt with the challenge of high inflation, which reached levels not seen since the early 1980s.

This hurt his approval ratings, despite strong job growth, a roaring stock market, and low unemployment.

Throughout his decades in government, Biden's personal life became intertwined with his political narrative.

He lost his wife and young daughter in a car accident, and his two sons were badly injured, all just weeks after the 1972 Senate election.

In 1988, he had surgery for two life-threatening brain aneurysms.

And in 2015, his elder son Beau died of brain cancer.

While president, Biden also grappled with his son Hunter's legal issues.

The younger Biden became the first child of a sitting President to be convicted of criminal charges when he was found guilty of falsely claiming to be drug-free when applying to buy a handgun.

Republicans also targeted Hunter Biden's overseas business dealings.

Both Bidens denied wrongdoing.

For over half a century, Biden became known as an affable public figure, with a penchant for saying what he thought.

No one ever doubts I mean what I say the problem is I sometimes say all that I mean.

But he also became known for his gaffes, which raised questions about his ability to serve as the oldest president in American history.

Poor kids are just as bright and just as talented as white kids.

Keep alive the truth and honor of the Holocaust, horror of the Holocaust.

Those concerns only heightened when he launched his 2024 re-election bid.

In June, a lackluster debate showing led to calls for Biden to step away from his re-election campaign.

That decision brought a surprising end to a political career that gave Biden a central role in the nation's wars, diplomacy, and pressing domestic battles for more than 50 years.