AMNA NAWAZ: Tomorrow, South Carolinians head to the polls in that state's Republican primary race.

South Carolina is often seen as a bellwether, with its first-in-the-South contest.

And Nikki Haley has spent more money and time on the ground in her home state than former President Trump.

But, as Lisa Desjardins reports, it's Mr. Trump that seems to maintain a strong hold on the electorate there.

LISA DESJARDINS: On her home turf this week, former Governor Nikki Haley said she's America's last chance at normalcy... NIKKI HALEY (R), Presidential Candidate: No drama, no vendettas, just results and getting work done for the American people.

LISA DESJARDINS: ... and the only candidate that can beat President Joe Biden.

NIKKI HALEY: As much as we want to turn our country around, we can't do that if we don't win.

And Donald Trump can't win a general election.

LISA DESJARDINS: In Sumter, a Central South Carolina city known for its nearby Air Force base, Haley's words resonated with Vietnam and Gulf War veteran Fred Parent.

FRED PARENT, Nikki Haley Supporter: Trump's about himself.

And that's not the way a public worker should be.

It should be about the whole country.

And he is a worker.

He works for us.

LISA DESJARDINS: And with longtime Republican Tina Martinez.

TINA MARTINEZ, Nikki Haley Supporter: The country is in a place where we need stability.

We need a little bit of a sure thing.

The American dream is kind of pretty much on life support.

I didn't think I'd ever be voting for a woman for president.

I want her to see that it's possible for her, especially as a minority woman as well.

LISA DESJARDINS: But Haley trails Trump here by a chasm of 30 points, on average, with Trump routinely polling at 60 percent and higher.

DONALD TRUMP, Former President of the United States (R) and Current U.S. Presidential Candidate: You're not supposed to lose your home state.

It shouldn't happen anyway.

And she's losing it bigly, big.

I mean, really -- I said bigly.

And bigly... (LAUGHTER) LISA DESJARDINS: A lot is at stake for Haley in this first-in-the-South primary.

GIBBS KNOTTS, College of Charleston: One reason it's a good predictor is because of the Super Tuesday primaries that come pretty quickly afterwards.

And a lot of those primaries are in the South.

LISA DESJARDINS: Gibbs Knotts is a professor of political science at the College of Charleston.

He says South Carolina is a bellwether, known for having voted for the party's eventual nominee nearly every time for the past 40 years.

GIBBS KNOTTS: It's not necessarily that South Carolina has just gotten really lucky.

We think it's actually because South Carolina is a pretty good predictor, based on the representativeness of the Republican voter here.

LISA DESJARDINS: But, earlier this week, Haley said she's not quitting.

NIKKI HALEY: When the country's future is on the line, you don't drop out.

You keep fighting.

South Carolina will vote on Saturday.

But, on Sunday, I will still be running for president.

LISA DESJARDINS: Still, the independent voters that pulled Haley closer to Trump, particularly in New Hampshire, are few and far between in South Carolina, with the most conservative electorate yet.

Northwest, in the state's foothills, Pastor Todd Black says he doesn't tell his congregation how to vote, but they already agree on the candidate and issues.

REV.

TODD BLACK, Pastor, Turning Point Free Will Baptist Church: How many of you are tired of going to the grocery store spending $100 and lucky to come out with two little bags, right?

MAN: Yes.

WOMAN: Amen.

LISA DESJARDINS: Black says he supports Trump because the former president's policies on social issues like abortion and religious freedom more closely align with his, even if Trump himself isn't perfect.

REV.

TODD BLACK: If he says he is a Christian, that's all I can go by.

But let me say this.

We're not electing a pastor.

We're electing the president of the United States.

And the more that they come at him with all of this stuff, when people see that, they're saying, you know what?

If they're trying to take him down like this and take away his rights, then they may come after me.

LISA DESJARDINS: Trump supporter Brian Winebrenner is in church leadership, and he's proud of his day job at the local BMW manufacturing plant.

BRIAN WINEBRENNER, Donald Trump Supporter: We build cars for the whole world.

I like the fact that we build in America.

And I like his stance on, if you want to come to our country as a person, then you do it the right way.

GOV.

HENRY MCMASTER (R-SC): New Hampshire is for Trump.

South Carolina is too.

LISA DESJARDINS: And it's Trump that gained the endorsement of nearly all of the top South Carolina elected Republicans, including Governor Henry McMaster and state Senators Lindsey Graham and Tim Scott.

And Knotts says Haley angered some power players in the Statehouse during her six years as South Carolina governor.

GIBBS KNOTTS: She really fought against the good old boy network, and one of the things she did was made sure that people had to -- you couldn't just voice-vote on something.

There had to be a record.

And so she wanted to hold legislators more accountable.

The downside to that, of course, is that she didn't -- she made some enemies, when you're going in and trying to change the system.

LISA DESJARDINS: But shoe store owner Zoe Owen says that anti-establishment approach is what attracted her to Haley years ago.

ZOE OWEN, Foot Saviv: It was just very exciting.

It was a new day, because here we had a person completely from the outside, not a political class coming in.

The state of South Carolina, I have so much faith in us.

And we know Nikki Haley.

And she is going to get rid of the extremism that's in Washington right now.

She's going to make us normal again.

(LAUGHTER) LISA DESJARDINS: Owen campaigned for then-state Representative Haley during her governor's race and says former President Trump's tariffs on China impacted her business directly.

ZOE OWEN: It was not good for the shoe business.

I question whether it was good for America.

Donald Trump's a big business guy, I mean, but he -- so he doesn't have the pulse on what it really feels like, if you don't sell a shoe, you don't eat spaghetti on Monday.

You eat beans on Monday.

LISA DESJARDINS: Still, Trump's appeal runs strong through this state, with voters who say he's just like them.

MEGAN MULLIKEN, Donald Trump Supporter: He's not somebody that can be puppeted around, which we see a lot in politics.

So I want somebody to stand in my place, because we don't have a voice in Washington as much as he does.

LISA DESJARDINS: The state has its first chance in generations to see a South Carolinian as a presidential nominee.

But Trump hopes to make history instead by convincing voters here that he's more like them than one of their own.

For the "PBS NewsHour," I'm Lisa Desjardins.