Super Tuesday: What is Super Tuesday? Which US states are voting for election presidential candidates? Will Donald Trump and Joe Biden win?

Super Tuesday will involve millions of voters in 15 states and one US territory choosing their preferred presidential candidate

Republican voters in 15 US states and one US territory will choose their preferred presidential candidate in what has become known in the election calendar as Super Tuesday.

Democrat voters will also go to the polls in 14 of the same states and the territory. Super Tuesday accounts for a third of the total number of delegates allotted to the final decision when they represent their state at national party conventions – 865 Republican and at least 1,420 Democrats.

What is Super Tuesday?

Donald Trump and Joe Biden are battling for their respective party nominations. Picture: Getty Images

Today, millions of US voters will go to the polls in Alabama, Alaska, Arkansas, California, Colorado, Maine, Massachusetts, Minnesota, North Carolina, Oklahoma, Tennessee, Texas, Utah, Vermont, Virginia and the US territory of American Samoa.

Democrats will vote in the same states except Alaska. The party will also hold a vote in American Samoa. The results of the Democrat contest in Iowa will also be revealed. The poll has been held by post and has taken some time to be completed.

What has happened in the primaries and caucuses so far?

On Monday, Donald Trump won the North Dakota Republican presidential caucuses, ahead of former UN ambassador Nikki Haley.

Republican presidential candidate, former President Donald Trump will face votes for the presidential candidate in 15 states on the day known as "Super Tuesday".

The results resume Mr Trump’s winning streak, which was briefly interrupted on Sunday when Ms Haley notched her first victory of the campaign in the District of Columbia’s primary.

The race began in January, when Mr Trump took his first victory of the campaign, in Iowa. The caucus is always regarded as the first litmus test of the political mood, which can have an influence over voting in other states.

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Who else is running against Donald Trump?

US President Joe Biden's Democrat party will vote for their preferred candidate in 14 states and one US territory.

California alone has 169 delegates and Texas 161 for the Republican national party decision, meaning the results in those two states are highly significant. Both of those are expected to go in Mr Trump’s favour.

Ms Haley is Mr Trump’s main rival. However, there has been talk that if Super Tuesday goes in the former president’s favour, she could consider dropping out of the race altogether.

Mr Trump had a different kind of victory earlier this week, when the US’s highest court ruled he should remain on Colorado’s primary ballot, rejecting a challenge to his eligibility for another term that could have seen him removed from ballots across the US. The Supreme Court ruled the 14th Amendment did not allow states to bar the former president from the ballot.

Most other Republican candidates dropped out of the campaign before the vote even began.

Who is Joe Biden’s opposition?

Like Mr Trump, incumbent president Mr Biden is a frontrunner in his campaign. However, he is not without his challenges.

Mr Biden, 81, is the oldest person to ever serve as president, something which his closest – albeit still far away – rival, congressman Dean Phillips, has pointed out repeatedly as part of his campaign strategy.

His popularity ratings have fallen recently and he has taken a hit in support over the Israel-Gaza war. Last month in Michigan, 13 per cent of voters said they were "uncommitted", rather than backing the president, due to protests over Mr Biden’s support for Israel.

Self-help author Marianne Williamson is also running against him.