The current president used a speech given in Philadelphia to slam his predecessor.
“Too much of what’s happening in this country today is not normal,” Biden said.
“Donald Trump and the MAGA Republicans represent an extremism that threatens the very foundations of our Republic.”
The acronym MAGA references Trump’s slogan Make America Great Again, and has become shorthand for the former president’s ideology.
Biden specified he was not criticising all members of the opposition party, many of whom he has worked with as president.
“MAGA Republicans do not respect the Constitution,” Biden said.
“They do not believe the rule of law. They do not recognise the will of the people, they refuse to accept the results of a free election.
“You can’t love your country only when you win.”
Biden said the Republican party is “dominated, driven and intimidated” by Trump.
“MAGA forces are determined to take this country backwards,” he said.
“Backwards to an America where there is no right to choose, no right to privacy, no right to contraception, no right to marry who you love.”
The speech has drawn the ire of Republicans, who took umbrage at the strongly partisan tone during a primetime address.
They also criticised Biden for giving a speech flanked by uniformed marines.
Senator Lindsey Graham said Biden should “stop lecturing and change your policies”.
“With all due respect Mr President, there’s nothing wrong with America’s soul,” he said.
“The American people are hurting because of your policies.”
Republican congresswoman Marjorie Taylor Greene posted a clip on Twitter which replaced Biden’s face with Adolf Hitler’s, and put swastikas behind him.
“I guess when President Butterbeans is frail, weak, and dementia ridden, the Hitler imagery was their attempt to make him look ‘tough’ while he declares war on half of America as enemies of the state,” she tweeted.
The speech was delivered outside Independence Hall, the building in Philadelphia where the constitution was adopted in 1787.
Biden has seen a bounce in the polls, climbing more than ten points in recent weeks.
Despite the climb, he is still well underwater in approval ratings, with more Americans disapproving of him than approving.
While it was assumed Democrats would lose control of Congress in the midterm election in November, polling and special election results have indicated this may not be the case.
Mary Peltola yesterday won a special election for Alaska’s seat in the House of Representatives, the first win for a Democrat there since 1972.