Donald Trump has continued his dominance of the Republican candidate race on “Super Tuesday”, using his victories to warn that the United States is a “very divided country” because of President Joe Biden.

Trump and Biden are all but certain to go head-to-head for the presidency later this year, after both swept a series of primaries and caucuses on Wednesday (AEDT) held to determine who would lead their parties to the US election in November.

Despite Biden losing the vote in American Samoa and Trump in Vermont, the pair swept every other contest with the property tycoon delivering a typically wild speech at his Mar-a-lago resort late into the evening US time.

“This was an amazing night and an amazing day, it’s been an incredible period of time in our country’s history,” Trump said.

“We have a great Republican party with tremendous talent and we want to have unity and we’re going to have unity and it’s going to happen very quickly.

“Never happened here. It happens in other countries, but they’re third world countries. And in some ways, we’re a third world country.”

Trump also attacked migrants and pledged to shake up America’s energy sector.

“They tell me there’s never been anything like this … it’s been an incredible period of time in our country’s history. We’re going to do something that frankly nobody’s been able to do for a long time.

“We’ve watched our country take a great beating over the last three years, and nobody thought a thing like this would be possible.”

Biden’s reaction to his Super Tuesday domination came after Trump’s in the form of a written statement.

“Tonight’s results leave the American people with a clear choice: Are we going to keep moving forward or will we allow Donald Trump to drag us backwards into the chaos, division, and darkness that defined his term in office?” Biden said.

Trump celebrates his victories with supporters on Wednesday (AEDT). Photo: Getty

“If Donald Trump returns to the White House, all of this progress is at risk. He is driven by grievance and grift, focused on his own revenge and retribution, not the American people. He is determined to destroy our democracy, rip away fundamental freedoms like the ability for women to make their own health care decisions, and pass another round of billions of dollars in tax cuts for the wealthy — and he’ll do or say anything to put himself in power.

“Today, millions of voters across the country made their voices heard — showing that they are ready to fight back against Donald Trump’s extreme plan to take us backwards.”

How the votes fell

Trump on Tuesday won the Republican votes in California, Alabama, Arkansas, Colorado, Maine, North Carolina, Oklahoma, Tennessee, Texas and Virginia, brushing aside former United Nations Ambassador Nikki Haley, his lone remaining rival, whose campaign no longer has an viable path to the nomination.

With more than one-third of Republican delegates up for grabs across 15 states on Super Tuesday, Trump’s commanding performance all but clinched his third consecutive presidential nomination, though he will have to wait at least one or two more weeks to mathematically eliminate Haley.

The incumbent Biden had been expected to sail through the Democratic contests, though activists opposed to his strong support of Israel urged Muslim Americans and progressives to cast “uncommitted” protest votes in Minnesota as they did before in Michigan.

The president easily won in California, Alabama, Arkansas, Colorado, Iowa, Maine, Massachusetts, North Carolina, Oklahoma, Tennessee, Texas, Vermont and Virginia, Edison projected. He also won a mail-in vote in Iowa that ended on Tuesday.

Another campaign between Trump, 77, and Biden, 81 – the first repeat US presidential match-up since 1956 – is one few Americans seem to want. Opinion polls show both Biden and Trump have low approval ratings among voters.

Immigration and the economy are leading concerns for voters in both parties, Edison exit polls in California, North Carolina and Virginia showed. A majority of Republican voters in those states said they backed deporting illegal immigrants. Trump, who frequently denigrates migrants, has promised to mount the largest deportation effort in US history if elected.

Trump, who has dominated the Republican campaign despite facing a litany of criminal charges, has won all but one of the contests so far, winnowing a sprawling Republican field of candidates down to two.

Trump’s advisers have said they expect him to formally secure the majority of Republican delegates no later than March 19, when two-thirds of the states will have voted.

He is scheduled to begin his first criminal trial six days later in New York, where he is charged with falsifying business records to conceal hush money payments to a porn star during his 2016 presidential run.

Biden said the elections were a chance to take on “the extreme division and violence the MAGA Republicans are pushing,” using the acronym for Trump’s Make America Great Again slogan.

Pop megastar Taylor Swift encouraged her fans to vote in a post on Instagram, though she did not endorse specific candidates. Biden’s campaign is hopeful Swift will eventually back his candidacy, as she did in 2020.

Haley’s challenge has highlighted some of Trump’s potential general election vulnerabilities. She has reached 40 per cent in some state contests and argues that shows independents and moderate Republicans harbour unease about a second Trump term.

About one-third of North Carolina voters said Trump would not be fit to serve as president if he was convicted of a crime, while in Virginia, 53 per cent said he would be fit for the office if convicted.

In addition to the New York case, Trump faces separate federal and Georgia state charges for election interference, though it is unclear whether either case will reach trial before November’s election. He also faces federal charges for retaining classified documents after leaving office.

Trump has pleaded not guilty in all four criminal cases.

Biden faces his own weaknesses, including widespread concern about his age. He is already the oldest US president in history.

– with AAP