President Joe Biden warned that "equality and democracy are under assault" in the United States. He said former President Donald Trump and extremist "MAGA Republicans" threaten the foundations of the country.

US President Joe Biden on Thursday warned that America's democracy was being threatened by what he called "extremists."

During a prime-time speech at Independence Hall in Philadelphia, Biden took direct aim at former President Donald Trump and his "Make America Great Again" (MAGA) supporters saying that "Donald Trump and the MAGA Republicans represent an extremism that threatens the very foundations of our republic."

Biden said, America was "in a battle for the soul of the nation."

"Equality and democracy are under assault," Biden said. "We do ourselves no favor to pretend otherwise."

Trump's MAGA followers taking the US 'backwards'

Biden cautioned that: "MAGA forces are determined to take this country backwards. 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."

Biden called for Americans across the political divide, and specifically mainstream Republicans to come out in defense of the country's democracy which he said could not be guaranteed.

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

Biden's toughening stance ahead of midterm elections

With the midterm elections taking place in November, Biden's speech has formed part of growing Democrat broadsides aimed at Trump-aligned Republican politicians.

Focus on hardline followers of the former president has marked an apparent shift in the current administration's strategy, when compared to Biden's first year in office, when he had appeared loathe to even mention Trump by name.

Biden was careful in his wording so as not to lump all Republicans under the same banner and made repeated reference to Trump and MAGA Republicans. "There are far more Americans, from every background and belief, who reject the extreme MAGA ideology, than those who accept it," Biden said.

"Not every Republican, not even a majority of Republicans, are MAGA Republicans," Biden said. "But there's no question that the Republican Party today is dominated by Donald Trump and the MAGA Republicans."

In a statement, Iowa GOP chairman Jeff Kaufmann said that Biden was using the tactics of an authoritarian regime and was "trying to turn his political opponents into an enemy of the state."

Last week Biden likened "MAGA philosophy" to "semi-fascism," something that did not sit well with Republican Senate Minority Leader Kevin McCarthy who said that it "vilifies" millions of "hardworking, law-abiding citizens."