Super Tuesday is the name given to the day when the largest number of US states are given the chance to cast votes for Republican and Democratic candidates.
It is usually seen as a turning point in most presidential campaigns, and a key indicator as to who the nominees will be from each party. It narrows the field.
No doubt, it will clarify the future of the five remaining Republican candidates - Donald Trump, Ted Cruz, Ben Carson, John Kasich, and Marco Rubio. On March 1, a total of 12 states and one territory will hold their respective primaries or caucuses.
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Super Tuesday and who gets left behind
For both Republicans and Democrats, Super Tuesday comes down to amassing delegates. For Republicans, 595 delegates are at stake. For Democrats, there are 1,004.
Considering Republican candidates need 1,237 delegates to win the party's nomination and Democrats need 2,383, Super Tuesday is one of the most important days in the US presidential election.
This year there is an expanded cast of Super Tuesday states. Alabama, Arkansas, and Texas have joined Super Tuesday, and Minnesota has also scheduled its primary on the same date.
In short, Super Tuesday, which covers a broad swath of the United States - and politics of all persuasions - is a potent realisation of both the economic staying power and organisational skills of all of the candidates.
For Democrats, this will mean a real stress test for grassroots campaigns, such as the one currently being run by Bernie Sanders.
Large primary events such as Super Tuesday inevitably favour well-funded candidates like his rival Hillary Clinton.
Within the ranks of the Republicans, only Donald Trump, Ted Cruz and Marco Rubio remain viable candidates for Super Tuesday and beyond.
Senator Cruz's home state of Texas is holding one of the primaries on March 1, and Cruz is relying on strong evangelic support.
Trump, of course, is expected to dominate: he is currently polling at 37.5 percent. Rubio is considered the party's compromise candidate.
Super Tuesday delegate system
More delegates can be won on Super Tuesday than any other day of the election.
Candidates will receive delegates based on the percentage of votes they receive.
In Alabama, Republican candidates will be competing for 50 delegates.
Sanders and Clinton are competing for 60.
The biggest Super Tuesday trophy for candidates in both fields is Texas, which offers 155 delegates to Republicans and 252 delegates to Democrats.
Donald Trump and the GOP scramble for survival
In their battle to outflank each other and become the main rival to Donald Trump, Super Tuesday is a battle over fundraising for both Ted Cruz and Marco Rubio. So far, Cruz has proved to be more popular with donors.
He entered this month with more than twice the amount of money than Rubio. The Texas Senator has also consistently out-fundraised Rubio in the 11 states that will stage Super Tuesday.
Last month, Cruz raised more than $1.8m from Super Tuesday battlegrounds – in comparison, Rubio raised around half that amount, $774,000.
It has been widely predicted the GOP - Grand Old Party - field will narrow after Super Tueday and either Kasich or Carson, or possibly both, will have to withdraw from the race.
The remaining candidates have large primaries ahead of them, including Florida, Illinois, North Carolina and Missouri, on March 15.
New York will vote on April 19 after which there is another multi-state primary on June 7 when California, Montana, New Mexico, New Jersey and the Dakotas vote.
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Source: Al Jazeera