In a 68-minute address to Congress, Biden, a Democrat, drew sharp contrasts with his Republican rival and gamely challenged Trump's supporters in the chamber during a speech that was watched as much for the 81-year-old president's performance as it was for his policy proposals.
Biden charged Trump, his Republican challenger in the November 5 election, with burying the truth about the January 6, 2021, Capitol assault, bowing to Russian President Vladimir Putin and blocking a bill to tighten restrictions at the US border with Mexico.
On the Middle East, the president said he had been working for an immediate ceasefire to last six weeks between Hamas militants and Israel, and he warned Israel against using aid to Gaza as a bargaining chip.
The greater thrust of his remarks focused on Trump, though Biden did not mention him by name.
Biden opened by declaring democracy under threat at home and abroad and criticizing Trump for inviting Putin to invade Nato nations if they did not spend more on defense.
"Now my predecessor, a former Republican president, tells Putin, quote, 'Do whatever you want,'" Biden said. "I think it's outrageous, it's dangerous and it's unacceptable."
Biden, who pressed Congress to provide additional funding to Ukraine for its war with Russia, also had a message for Putin: "We will not walk away."
Trump, in a response on his Truth Social platform, responded with criticism of Biden. "He said I bowed down to the Russian Leader. He gave them everything, including Ukraine," he said.
The speech gave Biden, who is suffering from low approval ratings, a chance to speak directly to millions of American television viewers about his vision for another four-year term.
He used the opportunity to draw contrasts with Trump over abortion rights and the economy, and he directed several barbs at Republican lawmakers in the chamber with off-the-cuff banter that appeared designed to assuage concerns about his age and mental acuity.
Biden was directly challenged by Republican Representative Marjorie Taylor Greene, who heckled him over Laken Riley, a woman recently killed, allegedly by an immigrant in the United States illegally.
Biden acknowledged Riley - and then, in a reference to efforts to reduce gun violence, referred to greater numbers of people killed in incidents unrelated to migrants in the country.
BIDEN ASSAILS TRUMP, REPUBLICANS
Biden accused Trump and Republicans of trying to rewrite history about the January 6, 2021, Capitol riot by the former president's supporters seeking to overturn Biden's 2020 victory.
"My predecessor and some of you here seek to bury the truth about January 6. I will not do that," Biden said, a signal that he will emphasize the issue during his re-election campaign. "You can't love your country only when you win."
He knocked Republicans for seeking to roll back healthcare provisions under the Affordable Care Act, also known as Obamacare, and driving up deficits, and jibed them for taking money from legislation they had opposed.
Biden faces discontent among progressives in his party about his support for Israel in its war against Hamas, but the mood among Democrats in the chamber was rapturous. They greeted Biden with cheers and applause, prompting him to quip that he should leave before he even began.
Trump, meanwhile, sent a steady stream of messages blasting Biden on Truth Social. "He looks so angry when he’s talking, which is a trait of people who know they are 'losing it,'" Trump wrote. "The anger and shouting is not helpful to bringing our Country back together!"
Opinion polls show Biden and Trump, 77, closely matched in the race. Most American voters are unenthusiastic about the rematch after Biden defeated Trump four years ago.
Trump, facing multiple criminal charges as he fights for re-election, says he plans to punish political foes and deport millions of migrants if he wins a second White House term.
Biden emphasized his support of abortion rights and pledged to make them the law of the land if Americans voted in enough Democratic lawmakers to do so.
He also renewed his quest to make wealthy Americans and corporations pay more in taxes, unveiling proposals including higher minimum taxes for companies and Americans with wealth over $100 million. Any such tax reform is unlikely to pass unless Democrats win strong majorities in both houses of Congress in the November vote, which is not forecast.
Biden proposed new measures to lower housing costs, including a $US10,000 tax credit for first-time homebuyers - an acknowledgement of consumers' distress over high mortgage interest rates - while boasting of U.S economic progress under his tenure.
The US economy is performing better than most high-income countries, with continued job growth and consumer spending. But Americans overall give Trump better marks in polls for economic issues.
BIDEN OUTLINES PLAN FOR GAZA PORT
Biden sought to cool anger among many Democrats over his support for Israel's offensive in Gaza following the October 7 Hamas attacks. He announced that the US military will build a port on Gaza's Mediterranean coast to receive humanitarian assistance by sea.
"To the leadership of Israel I say this: Humanitarian assistance cannot be a secondary consideration or a bargaining chip. Protecting and saving innocent lives has to be a priority," he said.
The president's wife's guests for the speech include Swedish Prime Minister Ulf Kristersson, who was in Washington as Sweden formally joined Nato on Thursday, two years after Russia's invasion of Ukraine.
Biden closed his speech with a reference to his age, saying he had been told during his career that he was both too young and too old. "Whether young or old, I’ve always known what endures," he said.
He highlighted Trump's age being close to his. "Now other people my age see it differently," he said, referring to their differing visions about America.
US Senator Katie Britt of Alabama, who delivered Republicans' formal response to Biden, attacked him over immigration and the economy.
“The true, unvarnished State of our Union begins and ends with this: Our families are hurting. Our country can do better,” she said.
