President Joe Biden warned that “equality and democracy are under assault” in the US as he sounded an alarm about his predecessor, Donald Trump.

The President labelled “MAGA Republican” adherents an extremist threat to America and its future.

Mr Biden used his prime-time speech at Independence Hall in Philadelphia to argue that Mr Trump and “Make America Great Again” allies are a challenge to nation’s system of government, its standing abroad and its citizens’ way of life.

“Donald Trump and the MAGA Republicans represent an extremism that threatens the very foundations of our Republic,” Mr Biden declared.

He continued by saying that the former president’s supporters “are determined to take this country backward”, “promote authoritarian leaders” and “fan the flames of political violence”.

Mr Biden added: “(They want to take the country) 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.

“For a long time, we’ve reassured ourselves that American democracy is guaranteed. But it is not. We have to defend it. Protect it. Stand up for it. Each and every one of us.”

The explicit effort by Mr Biden to marginalise Mr Trump and his adherents marks a sharp turn for the President, who preached his desire to bring about national unity in his Inaugural address.

White House officials said it reflects his mounting concern about Trump allies’ ideological proposals and relentless denial of the nation’s 2020 election results.

Mr Biden, who largely avoided even referring to “the former guy” by name during his first year in office, has grown increasingly vocal in calling out Mr Trump personally.

Now, emboldened by his party’s recent legislative wins and wary of Mr Trump’s return to the headlines, Mr Biden is sharpening his attacks.

Mr Biden’s allies stress that he is not rejecting the entirety of the GOP and is calling on traditional Republicans to join him in condemning Mr Trump and his followers.

Delivering a pre-emptive rebuttal from Scranton on Thursday evening, House Republican leader Kevin McCarthy accused Mr Biden of trying to divide Americans, and blasted the Democrats’ record in Washington, pointing to rising inflation, crime and government spending.

“In the past two years, Joe Biden has launched an assault on the soul of America, on its people, on its laws, on its most sacred values,” he said. “He has launched an assault on our democracy. His policies have severely wounded America’s soul, diminished America’s spirit and betrayed America’s trust.”

Mr Biden’s appearance on Thursday night was promoted as an official, taxpayer-funded event, a mark of how the president views defeating the Trump agenda as much as a policy aim as a political one.