Americans begin voting in Super Tuesday primaries

The presidential election to replace Barack Obama will take place on November 8th.

As voters head to the polls Super Tuesday over 600 Republican and 800 Democratic delegates are up for grabs. That could cost Messrs Cruz and Rubio, who will not be allocated delegates if they don't reach a state's voting threshold, leaving the field open to Mr Trump.

Super Tuesday is about more than just the huge number of voters expected to come that day.

Before the results rolled in during the SC primary last month, Democratic presidential candidate Bernie Sanders was already on to the Super Tuesday States, but he wasn't the only one. Republicans also have a contest in Alaska, while Democrats vote in Colorado.

The states in green are where both parties will hold their primaries; those shown in gold are where both parties will hold caucuses, and those in red are where the Republicans will hold caucuses.

What's the difference between a primary and a caucus? Polls in Arkansas close at 8:30 p.m ET, while Texas, Colorado, and Minnesota will close at 9 p.m. The only contest that will end past the bedtime of most viewers is Alaska, where polls close at 1 a.m. ET. The party expects it will easily pass previous caucus records set in 2008. What about the other states?

A primary is a more straight-forward vote, but again there are a number of different types of primary to consider. The number of delegates and how they are selected varies from state to state.

IL holds its primary election March 15. Until 2004, these Southern primaries were held the week following Super Tuesday. Ted Cruz, R-Texas, speaks at the National Religious Broadcasters convention. And the vote isn't a winner-take-all affair; even losers can pick up some delegates because they are awarded proportionally depending on the vote in each congressional district and statewide.

How many delegates do the candidates have so far?

What is a delegate and why are they important? That presidential election year, former Minnesota Sen.

The candidate who wins the most delegates will win the nomination, but the number required differs for both parties.

Republican Donald Trump and Democrat Hillary Clinton hope things break their way in the delegate-rich Super Tuesday, the busiest day of the 2016 primaries.

Voters get the chance to tell the parties who they would send to the White House, and candidates who seemed like a long shot or an underdog can suddenly get momentum behind them with some big wins. So if Silver's estimates hold true, Sanders needs to secure some major wins on Super Tuesday to stay in the race. Polls have suggested Ted Cruz, who represents the state in the U.S. Senate, is in the lead among Republicans contenders, followed by Donald Trump. According to Nate Silver at FiveThirtyEight, Bernie Sanders needs to win Colorado, Massachusetts, Minnesota, Oklahoma, Tennessee, and Vermont on Super Tuesday to clinch the Democratic presidential nomination. Clinton would get the remaining 13.