Trump and Haley will face off in South Carolina. Here's what you need to know.

The quartet of early Republican nominating contests will soon end with the South Carolina primaries, following the Iowa and New Hampshire caucuses last month and the Nevada caucuses and caucuses this month.

Here's what you need to know.

When are the Republican primaries in South Carolina?

Saturday February 24.

Who can participate?

South Carolina has no formal party registration, so registered voters can participate in the primaries regardless of whether they identify as Republicans, Democrats or independents.

However, if you voted in the Democratic primary this month, you cannot also vote in the Republican.

How can I vote?

On election day, polling stations are open from 7 a.m. to 7 p.m. (You can find your polling place on Election Day here.) You can also vote early from now through February 22 – except between February 18 and 19 – but your early voting location may be different from your polling place on Election Day, so make sure you look here.

Either way, you must show photo ID.

Some South Carolinians can vote absentee by mail. You can check whether you qualify for this here.

If you are not yet registered to vote, unfortunately it is too late to do so for this primary; the deadline was last month. But you can find the information you need here to register in time for the non-presidential primaries in June – when voting will take place in congressional, state legislative and local elections – and the general election in November.

Who will be on the ballot?

Seven candidates are listed:

• The two main contenders, former President Donald J. Trump and Nikki Haley

• Two little-known candidates, Ryan Binkley and David Stuckenberg

• Three former candidates – Chris Christie, Ron DeSantis and Vivek Ramaswamy – who dropped their campaigns after the ballots were determined.

The vote will also include three questions on policy issues, but those results are not binding; they are intended for the Republican Party to gauge voter sentiment.

What are we looking at in South Carolina?

South Carolina could be the last stand for Ms. Haley's campaign.

It's her home state, and voters there twice elected her governor, so it appears to offer her a chance to compete closely with Mr. Trump — but Polls show her far behind. She has said she doesn't think she needs to win South Carolina to remain viable, but she needs to do better than New Hampshire (43 percent), which in turn was better than Iowa (19 percent). .

If she outperforms the polls, the momentum could carry her into Super Tuesday's 16-race race, where she would need to collect a lot of delegates to be competitive. (We're tracking delegate counts here.) If she doesn't, her path looks pretty bleak.

What happens now?

After South Carolina, the race moves to Michigan, where primaries for both parties will be held on February 27, as Democrats took the state a step further in their nominating process.

But because the Republican National Committee has not approved that change, it will award only a fraction of Michigan's delegates to the party's national convention based on those primary results. The rest of the state delegates will be determined later, during caucuses led by party insiders.

After February 27, the weeks of one-state-at-a-time campaigning end as the race moves on to Super Tuesday on March 5.