Republican presidential frontrunner Donald Trump won the Republican caucuses on Saturday in three states including battleground Michigan, as he further escalated his immigration rhetoric and accused US President Joe Biden of waging an immigration-based “conspiracy to overthrow the United States of America” as the Super Tuesday voting approached.

The former US president also won the Missouri and Idaho Republican caucuses on Saturday, according to data company Edison Research.

In all three states Mr Trump trounced Nikki Haley, his last remaining rival for the Republican presidential nomination, moving him closer to becoming his party’s White House standard-bearer and a likely general election rematch with President Joe Biden, a Democrat.

In Michigan, Mr Trump beat Ms Haley in all 13 districts taking part in the nominating caucuses, according to the state Republican Party. Overall, Mr Trump won with nearly 98pc per cent support: 1,575 votes to just 36 for Ms Haley.

Pete Hoekstra, the Michigan Republican Party’s chair, called it an “overwhelming, dominating victory”.

More than 1,600 party insiders participated in the presidential caucus in the western Michigan city of Grand Rapids, where they were choosing delegates for Trump or former UN ambassador, Ms Haley, for the party’s national nominating convention in July.

Ms Haley is fast running out of time to alter the course of the Republican nominating race. Next up is Super Tuesday this week, March 5, the biggest day in the primaries, when 15 states and one territory will vote.

With victories in Iowa, New Hampshire, Nevada, the US Virgin Islands, South Carolina, and now Michigan, Missouri and Idaho under his belt, Mr Trump is far and away the frontrunner in the race, with Ms Haley hanging on thanks to support from donors keen for an alternative to the former president.

For this election cycle, Michigan Republicans devised a hybrid nominating system, split between a primary and a caucus.

Mr Trump won the primary convincingly last Tuesday, securing 12 of 16 delegates up for grabs. He took all of Michigan’s remaining 39 delegates at stake on Saturday.

At one of the 13 caucus meetings, the participants – knowing Mr Trump would win easily -– decided to save time by simply asking anyone who backed Haley to stand up. In a room of 185 voting delegates, 25-year-old Carter Houtman was the only person who rose to his feet.

“It was a little lonely,” Mr Houtman told Reuters in an interview afterward. Mr Houtman said he would likely vote for Mr Trump in November’s general election if he is the nominee but felt it was important to stand up for his beliefs on Saturday.

“I didn’t like the way that Trump handled himself after the last election,” Mr Houtman said.

Dennis Milosch, 87, a Trump supporter, said the former president’s dominating win on Saturday underscored how the party has been transformed from one aligned with big business to one focused on the working class.

“Wherever he goes, whatever he does, he pays attention to, responds to, the average person,” Mr Milosch said.

Mr Trump’s victories in Missouri and Idaho netted him 54 and 32 delegates respectively. 

Trump says Biden border policies are ‘conspiracy’

Mr Trump, who has alleged without proof that Mr Biden is responsible for the various court indictments he faces, turned again to Mr  Biden’s border policies on Saturday, charging in North Carolina that “every day Joe Biden is giving aid and comfort to foreign enemies of the United States”.

“Biden’s conduct on our border is by any definition a conspiracy to overthrow the United States of America,” he went on to say in Greensboro, North Carolina. “Biden and his accomplices want to collapse the American system, nullify the will of the actual American voters and establish a new base of power that gives them control for generations.”

Similar arguments have long been made by people who allege Democrats are promoting illegal immigration to weaken the power of white voters — part of a racist conspiracy, once confined to the far right, claiming there is an intentional push by the US liberal establishment to systematically diminish the influence of white people, the Associated Press reported.

“Once again Trump is projecting in an attempt to distract the American people from the fact he killed the fairest and toughest border security bill in decades because he believed it would help his campaign. Sad,” Biden campaign spokesman Ammar Moussa said in a statement.

Mr Trump’s campaign stops came three days before Super Tuesday, with elections in 16 states, including North Carolina and Virginia, where thousands of enthusiastic supporters gathered for an evening rally in Richmond. The primaries will be the largest day of voting of the year ahead of November’s general election, which is shaping up as a likely rematch of 2020 between Mr Trump and President Biden.

Ms Haley also campaigned in North Carolina. Speaking to reporters after her event in Raleigh, about 80 miles away, she demurred on her plans after Super Tuesday.

“We’re going to keep going and we’re going to keep pushing,” she said, arguing a majority of Americans don’t want either Mr Biden or Mr Trump as the nation’s leader.

Much of Mr Trump’s speech in North Carolina focused on the slew of criminal charges he faces. While the former president has apparently harnessed his legal woes into a powerful rallying cry in the primaries, it is unclear how his message of grievance will resonate with the more moderate voters who will likely decide the general election.

“I stand before you today not only as your past and hopefully future president, but as a proud political dissident and a public enemy of a rogue regime,” Mr Trump said, railing against what he called an “anti-democratic machine’’.

At both rallies, Mr Trump played a recording of “Justice for All’’. the version of the Star-Spangled Banner that he collaborated on with a group of defendants jailed over their alleged roles in the January 2021 insurrection, whom he refers to as “hostages’’.

On Saturday, Mr Trump conjured images of  Mr Biden turning “public schools into migrant camps” and “the USA into a crime-ridden, disease-ridden dumping ground, which is what they’re doing’’.  

In North Carolina, a festive atmosphere surrounded the Greensboro Coliseum Complex ahead of Mr Trump’s rally. Supporters stood in a line that snaked through a web of metal barricades and extended hundreds of yards from the arena. License plates from North Carolina, Virginia and Tennessee filled the parking lot, where Trump flags flew alongside US and Confederate flags on many vehicles.

“We just love Trump,” said, Mary Welborn, who lives in nearby Thomasville and expressed that she was frustrated by the criminal prosecutions and civil judgments against the former president. “The way he’s being treated is insane. No other president has been treated this way,” she said.

In Richmond, supporters started lining up on Saturday morning for an evening rally at a convention centre. The entry lines stretched several blocks by mid-afternoon.