"He told the crowd to fight like hell. And all hell was unleashed," Biden said of the 2021 attack. "Then as usual he left the dirty work to others. He retreated to the White House."

Biden marked three years since the Jan. 6, 2021, attacks with his first major campaign speech of the year, applying the heat on Trump as he pushes against questions about his handling of the U.S. economy and his age, 81. Trump is 77.

Whether Biden's Friday speech will make an impact 10 months before Election Day - in a politically polarized country where voters get news and information from wildly different sources - remains to be seen.

But it set the tone and laid out the stakes of what is likely to be a bitter battle. Biden characterized Trump and his followers as dangerous outliers and asked Democrats, independents and "mainstream Republicans" who cherish U.S. democracy to back him.

"Democracy is on the ballot. Your freedom is on the ballot," he said.

Biden said Trump's re-election bid is based on trying to seek "revenge and retribution" against his political enemies. He reminded Americans that Trump has called his opponents "vermin," the "same exact language used in Nazi Germany."

"How dare he? Who in God's name does he think he is?" said Biden, lowering his voice to a whisper.

Trump, president from 2017 to 2021, who is leading the field for the Republican nomination for president, contested his defeat in the 2020 election, prompting thousands of his supporters to attack the U.S Capitol on Jan. 6, 2021. The failed bid to stop formal certification of the result resulted in the deaths of five people and injured dozens of police officers.