Florida will hold both its Democratic and Republican primaries on Tuesday, March 15. The polls will be open from 7 a.m. to 7 p.m. Eastern.

The state has a long tradition of being at the center of the presidential election every four years. It is no different during primary season with a lot at stake for both parties.

On the GOP side, the following four candidates remain in the race for the nomination: Ted Cruz, John Kasich, Marco Rubio and Donald Trump. Hillary Clinton and Bernie Sanders are fighting for the Democratic nomination.

Here’s what you need to know about each party’s Florida primary.

1. Florida Is a Closed Primary

Florida is a closed primary. This means to participate in either the Democratic or Republican primary, Florida voters have to be registered with that particular party. Florida residents had to be registered by February 16 to participate in either primary.

Early voting in Florida is from March 5-12. Voters will need a valid form of ID to participate in either primary. Click here for further details on acceptable forms of identification as well as the Florida voting FAQ page.

2. Marco Rubio Is a Large Underdog in His Home State

The Rubio campaign has made it clear their focus for weeks has been on his home state of Florida. Rubio got off to a slow start in the early primaries and caucuses. He now faces a must-win scenario in Florida to justify staying in the Republican race.

According to RealClear Politics, Trump is leading Rubio by an average of 16 percentage points in early polling. Florida is an important state given its large number of delegates along with the winner-take-all nature of the primary.

Trump has spent a great deal of time campaigning in Florida. He hosted both a Super Tuesday speech and a press conference in Florida following the March 6 elections in addition to several other Florida stops on the campaign trail.

3. Hillary Clinton Has a Sizable Lead in Florida

While primary results can go differently than early polling numbers, Clinton has a large lead in all the major early polls in Florida. According to RealClear Politics, she has an average lead of 25.6 percentage points over Sanders in Florida’s early polls.

The early Democratic polling numbers have been fairly accurate, especially in the Southeast, so far in the Democratic primary process. Clinton has dominated Sanders in the region thus far. Given the delegates are split proportionally based on the results, the Sanders campaign hopes to narrow the gap by the time of the March 15 primary.

4. The Winner of the Florida GOP Primary Will Take All the Delegates

Prior to the March 15 GOP primaries, the majority of early primaries and caucuses have used the proportional method to divide the delegates among candidates. This means the delegates have been divided among multiple candidates based on the results.

Florida represents the first major state so far to use the winner-take-all method of awarding the delegates. One candidate will win all of Florida’s 99 delegates.

On the Democratic side, Florida also represents a big prize with 246 delegates. The party uses the proportional method for each primary and caucus.

5. Mitt Romney Won the 2012 Primary

Romney had a double digit victory in the 2012 Florida GOP primary. He defeated Newt Gingrich by 14.5 percentage points to win all 50 delegates (the delegate number is different in 2016). Romney’s victory in Florida played a part in him going on to win the Republican nomination.

The Democratic party last visited Florida in 2008. Clinton had a sizable victory of 16.9 percentage points over Barack Obama in the 2008 Democratic primary. Despite her big Florida victory, she went on to lose the nomination to Obama.