Donald Trump said the US election will be “liberation day” for his supporters and “judgement day” for his enemies in a high-octane speech ahead of the South Carolina primary on Saturday night.

The former president, 77, vowed his second term would mean “revenge” for his opponents as he promised to “fire” Joe Biden, 81.

With Mr Trump on course to clinch his party’s nomination within weeks, his rousing, though often rambling, address to the Republican Party faithful was entirely focused on November’s general election.

The roughly 90-minute appearance at the Conservative Political Action Conference (CPAC) on the outskirts of the US capital was concentrated on crime, immigration, and foreign policy.

Should he return to Washington for a second term, Mr Trump said: “Your victory will be our ultimate vindication, your liberty will be our ultimate reward and the unprecedented success of the United States of America will be my ultimate and absolute revenge”.

“For hard-working Americans, November 5th will be our new liberation day,” he said.

“But for the liars and cheaters and fraudsters and censors and imposters who have commandeered our government, it will be their judgement day.”

He made no reference to his Republican challenger, Nikki Haley, whom he was expected to beat in her home state by as much as 27 points, according to polling aggregator FiveThirtyEight.

The 52-year-old Ms Haley has vowed to stay in the race until at least “Super Tuesday” on March 5, when 15 states vote.

But a humiliating rejection in South Carolina, where she served two terms as governor, may change that calculation.

Speaking ahead of Saturday night’s result, Karoline Leavitt, the Trump campaign’s national press secretary, told The Telegraph the former president was “feeling terrific”.

“We are so excited for President Trump to have another big victory tonight,” Ms Leavitt said.

“We feel really confident that our winning message and our unmatched ground game and the overwhelming support that he has from local and national Republican representatives from the state will propel us to victory.”

While at CPAC, Mr Trump also lashed out at Prince Harry, warning he would not “protect” him if he wins a second term, amid a legal challenge relating to the Duke’s visa application.

“I wouldn’t protect him. He betrayed the Queen. That’s unforgivable. He would be on his own if it was down to me,” Mr Trump told the Daily Express.

It comes as the US government has fought to block the public disclosure of the Duke’s visa application after his admission of drug use triggered a court challenge by the Heritage Foundation.

Meanwhile, Mr Trump has invested in courting the African American voters who were credited with powering Mr Biden’s 2020 bid.

The Republican frontrunner’s campaign believes he is gaining strength among black voters, although polls show an overwhelming majority still favour Mr Biden.

Addressing a gathering of black conservatives in South Carolina on the eve of its GOP primary, Mr Trump said black people are “on my side now” because they see him as a victim of discrimination.

At the black-tie event in Columbia, Mr Trump told the crowd: “You understand that. I think that’s why the black people are so much on my side now because they see what’s happening to me happens to them.”

The freewheeling address mixed Mr Trump’s stump speech staples with direct appeals to black voters.

His jokes touching on race were seized on by the Biden campaign, but did attract some laughter from the audience.

“The lights are so bright in my eyes I can’t see too many people out there,” Mr Trump said. “I can only see the black ones. I can’t see any white ones. That’s how far I’ve come,” he added.

Mr Biden’s team hit back at the “moronic” and “racist” comments from the former president.

Cedric Richmond, the co-chairman of the Biden-Harris campaign, said: “Though I may be disgusted, I am not at all surprised that Donald Trump would equate the suffering and injustice of Black people in America to consequences he now faces because of his own actions. 

“Donald Trump claiming that Black Americans will support him because of his criminal charges is insulting. It’s moronic. And it’s just plain racist. 

“He thinks Black voters are so uninformed that we won’t see through his shameless pandering. He has another thing coming. Trust me when I say, in November the very voting block that he continues to disrespect will make him eat these words.”