Joe Biden wiped away a tear at one point during his emotional victory speech, as he thanked South Carolina for reviving his campaign.

The former vice president used his early defeats in Iowa, New Hampshire and Nevada to frame today's result as a sign of resilience.

"All those of you who've been knocked down, counted out, left behind, this is your campaign," Mr Biden said.

"Just days ago, the press and the pundits had declared this candidacy dead. Now, thanks to all of you, the heart of the Democratic Party, we've just won and we own big.

"We are very much alive."

He said the campaign had "taken off", and urged Democratic voters in Super Tuesday states to "join us".

"As we celebrate tonight, let me talk directly to Democrats across America. Especially those who'll be voting on Super Tuesday. This is the moment to choose the path forward for our party. This is the moment, and it's arrived," said Mr Biden.

"The decisions you make will determine what this party stands for, what we believe, and what will get done.

"If Democrats nominate me, I believe we can beat Donald Trump.

"If the Democrats want a nominee who will build on Obamacare, not scrap it; take on the NRA, not protect them; stand up and give the poor a fighting chance, restore the middle class and not raise their taxes; keep the promises we make; then join us.

"If the Democrats want a nominee who's a Democrat. A lifelong Democrat. A proud Democrat. An Obama-Biden Democrat. Then join us."

Those lines were all very clearly designed to contrast Mr Biden with the frontrunner for the nomination, Bernie Sanders.

And so was the following argument about electability.

"We have the option of winning big or losing big. That's the choice. We need to build on the legacy of the most successful president of our lifetime, Barack Obama," he said.

"Win big or lose, that's the choice. Most Americans don't want the promise of revolution. They want more than promises, they want results.

"Talk is cheap. False promises are deceptive. And talk about revolution isn't changing anyone's life. We need real changes, right now. Something I've done my whole career."

Mr Biden then shifted away from policies and polling, and to the less tangible elements of politics.

"This is a battle for the soul of the United States of America. We are in an incredibly perilous moment," he said.

"We have to beat Donald Trump and the Republican Party, but here's the thing. We can't become like them."

He quoted the most famous line from America's Declaration of Independence – the one that says "all men are created equal".

"We've never fully lived up to it. But until this President, we've never walked away from it," said the former vice president.

As he neared the end of his speech, Mr Biden got personal. He spoke about the death of his son Beau in 2015, and how South Carolina had helped him recover.

Mr Biden and his wife Jill visited the state as it mourned in the wake of the Charleston church shooting that year. They were struck by the strength of its people.

"We needed to be healed. We needed whatever they were exuding. And with every season that's passed, they've gotten up and found purpose to live life worthy of the ones they'd lost," he said.

"We left here – having arrived in overwhelming pain – thinking we can do this. We can get through this.

"It's no small reason why I'm in this race. People like all of you here tonight, all around the country. The days of Donald Trump's divisiveness will soon be over."

He took a moment to wipe away a tear.

"This multi-ethnic country we call America can't survive unless we focus on our goodness," he continued.

"We can build a more perfect union, because the American people in the last few years have seen the alternative.

"No, think about it. They've seen how utterly mean, selfish, lack of any sense of empathy or concern for anyone else. A President who not only has horrible policies, but the way he mocks and makes fun of other people.

"Let's get back up. We're decent, we're brave, we're a resilient people. We're better than this President. So get up, take back our country."