Hillary Clinton’s decision to compare Donald Trump to Adolf Hitler has sparked outrage with allies of the former President labelling her comments “bitter” and “foul-mouthed”.

Clinton, 76, who lost to Trump in the 2016 US Presidential Election, warned the property-tycoon-turned-politician would endanger democracy by returning to the White House.

She said: “When I was secretary of state, I used to talk about ‘one and done’.

“What I meant by that is that people would get legitimately elected and then they would try to do away with elections, and do away with opposition, and do away with a free press.”

Clinton added: “Hitler was duly elected. All of a sudden somebody with those tendencies, dictatorial, authoritarian tendencies, would be like ‘OK we’re gonna shut this down, we’re gonna throw these people in jail.’

“And they didn’t usually telegraph that. Trump is telling us what he intends to do.”

Allies of the 45th President were quick to slam Clinton for her comments.

Mark Burns, who is dubbed as Trump’s Pastor, told GB News: “Hillary is a bitter, foul-mouthed, short-tempered, entitled kleptomaniac who clearly has psychological problems over her upset loss to Trump. I will be praying for her.”

Adolf Hitler welcomed by supporters in Nuremberg in 1933

“If anyone cared about what she thought, she would have been elected President,” a 2016 Trump campaign veteran added.

During her appearance on ABC yesterday, Clinton made clear her warning should be taken seriously.

“Trump is telling us what he intends to do,” she said. “Take him at his word.”

Hitler, who won the 1932 German federal election, sparked the Second World War by invading Poland and orchestrated the horrific extermination of around six million Jewish people during the Holocaust.

Donald Trump is the frontrunner for the GOP nominationREUTERS

Clinton’s comments come after it was revealed that Trump is reportedly discussing how to use the Justice Department to investigate political rivals and former allies who have been critical of him should he return to the White House.

He is also discussing invoking the Insurrection Act on his first day in office, which would allow him to use the US military domestically to quell protests and dissent.

Despite facing a number of legal obstacles, Trump is leading Joe Biden in a number of critical swing states.

An opinion poll conducted by Siena for the New York Times showed Trump ahead of the incumbent Commander-in-Chief in Arizona, Georgia, Michigan, Nevada and Pennsylvania.

Opinion polls suggest Biden is trailing Trump in several swing states

Victory in the 2024 US Presidential Election would make Trump just the second President to serve two non-consecutive terms in the Oval Office.

However, the general election campaign is not yet in full swing, with both men needing to win their respective primary races before turning their attention to November 5, 2024.

A number of Republican rivals are challenging Trump for the conservative crown but the 77-year-old is streaking ahead of his opponents in the opinion polls.

Biden is not facing as much of a significant challenge and is even stronger in current Democratic Party primary surveys.