Trump won the Republican votes in 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.
Donald Trump says his focus will be on Joe Biden after the vote, not reaching out to Nikki Haley. (AP PHOTO)
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 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 told Fox that his focus was on Biden, adding: "We're going to win every state tonight."
Former president Donald Trump is leading fellow candidate Nikki Haley in every Super Tuesday state. (AP PHOTO)
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.
Millions of Americans have voted on Super Tuesday, with Joe Biden and Donald Trump dominant. (EPA PHOTO)
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.
