Tempers and tensions were high Thursday as US President Joe Biden faced off against Republican rival Donald Trump in the first debate of the 2024 White House campaign.

Here are some of the key quotes from the evening:

Democracy

Biden: "And now he says that if he loses again, such a whiner that he is, that there could be a bloodbath."

Biden: "This guy has no sense of American democracy."

Trump, on political violence: "Of course, I believe that it's totally unacceptable."

Trump, asked if he would accept the results of the election: "If it's a fair and legal and good election, absolutely." 

Abortion

Trump, on the US Supreme Court's decision to overturn the right to abortion: "It's been a great thing."

Biden: "It's been a terrible thing."

Climate

Trump: "I want absolutely immaculate clean water, and I want absolutely clean air... I had the best environmental numbers ever. And my top environmental people gave me that statistic just before I walked on the stage, actually."

Biden: "I passed the most extensive, most extensive climate change legislation in history... The only existential threat to humanity is climate change, and he didn't do a damn thing about it."

Russian invasion of Ukraine

Trump, asked about Vladimir Putin's terms for ending the Ukraine war (by keeping the territory claimed by Russia and with Ukraine abandoning its bid to join NATO): "No, they're not acceptable."

Trump: "I will have that war settled between Putin and (Ukraine President Volodymyr) Zelensky as president-elect, before I take office on January 20."

Biden: "The fact is that Putin is a war criminal. He's killed thousands and thousands of people. And he's made one thing clear. He wants to reestablish what was part of the Soviet empire. Not just a piece, he wants all of Ukraine. That's what he wants. You think he'll stop there?"

Israel-Hamas war

Biden: "Hamas cannot be allowed to be continued... And by the way, they've been greatly weakened, greatly weakened. And they should be. They should be eliminated. But you've got to be careful (about) using certain weapons among population centers."

Trump: "You should let (Israel) go and let them finish the job" in Gaza. "He doesn't want to do it, he's become like a Palestinian, but they don't like him because he's a very bad Palestinian. He's a weak one."

Economy

Biden: When he became president "we had an economy that was in free fall... And so what we had to do was try to put things back together again. That's exactly what we began to do."

Biden: "He decimated the economy. Decimated the economy. That's why there was no inflation at the time. There were no jobs."

Trump: "Inflation's killing our country. It is absolutely killing us."

Immigration

Trump: "We had the safest border in history. Now we have the worst border in history. And people are dying all over the place. There's never been anything like it."

Biden: "There's no data to support what he said. Once again, he's exaggerating. He's lying."

Each other

Biden: "The only person on this stage who is a convicted felon is the man I'm looking at right now."

Trump: "When he talks about a convicted felon, his son is a convicted felon... He could be a convicted felon as soon as he gets out of office, Joe could be a convicted felon, with all of the things that he's done. He's done horrible things."

Biden: "What are you talking about? You have the morals of an alley cat."

Age

Biden, asked about concerns over his age: "This guy's three years younger, and a lot less competent."

Trump: "I took two tests, cognitive tests. I aced them, both of them, as you know, we made it public. He took none. I'd like to see him take one, just one, a real easy one, like go through the first five questions. He couldn't do it."

Golf

Trump: "He can't hit a ball 50 yards."

Biden: "I'd be happy to have a driving contest."