AMNA NAWAZ: It's the final countdown to Super Tuesday, when voters in 16 states will make their voices heard and a third of all Republican delegates are at stake.

The two remaining GOP candidates both tallied primary wins over the weekend and hit the campaign trail with their sights set on tomorrow.

Lisa Desjardins begins our coverage.

LISA DESJARDINS: At Wilber's Barbecue in Eastern North Carolina, the food has always been served with a side of politics.

LASHONA SCOTT, Head Cook, Wilber's Barbecue: Nobody gets mad if you're talking about politics while you eat because they're too busy focusing on trying to get their bellies full.

LISA DESJARDINS: The restaurant has hosted its fair share of politicians across its 60-year history, including Presidents George H.W.

Bush and Bill Clinton.

But in the days leading up to Super Tuesday and the state's presidential primary, the focus has been the next race for president.

RYAN HERRING, North Carolina Voter: I would like to see Donald Trump on it.

I don't really care about a career politician or somebody that's just going to talk a bunch of smoke.

LISA DESJARDINS: In this town hundreds of miles from the U.S.-Mexico border, immigration is top of mind for some voters.

RICHARD LANIER, North Carolina Voter: I think that immigration is a key issue for most Americans right now.

And I think that it's a big problem.

And the next one would be inflation.

A lot of families are suffering because of inflation.

(CHEERING AND APPLAUSE) DONALD TRUMP, Former President of the United States (R) and Current U.S. Presidential Candidate: I'm thrilled to be back.

LISA DESJARDINS: The former president, fresh off a trip to the border, seized on those concerns during a rally in North Carolina this weekend.

DONALD TRUMP: Our border is an open and gushing wound.

LISA DESJARDINS: Trump railed against the bipartisan immigration deal that he helped demolish last month.

He ramped up attacks on migrants and, aware that many voters see him as a threat to democracy, made unfounded accusations trying to pin the idea onto his rival, President Joe Biden.

DONALD TRUMP: Biden's conduct on our border is by any definition a conspiracy to overthrow the United States of America.

LISA DESJARDINS: The message resonated with the thousands of Trump supporters who lined up outside hours before he took the stage.

DIANE BROWN, North Carolina Voter: We're coming to support a man that has been brave enough to withstand all kinds of persecution.

And I love him.

I don't care what anybody says about him.

I freaking love him.

LISA DESJARDINS: But Trump's last remaining Republican rival, Nikki Haley, is staying in the fight, at least for now.

NIKKI HALEY (R), Presidential Candidate: We defeated a dozen of the fellows.

(CHEERING AND APPLAUSE) NIKKI HALEY: I just have one more I'm trying to catch up to.

LISA DESJARDINS: The former South Carolina governor won her first primary contest yesterday, earning all of the GOP delegates in Washington, D.C., and making history for a Republican woman.

She hopes the endorsement of two moderate senators, Lisa Murkowski of Alaska and Susan Collins of Maine, give her momentum heading into tomorrow, when Republicans in both states head to the polls.

Haley has said she's not looking past tomorrow, but if Trump is the GOP nominee, she opened the door to abandoning her pledge to support the party's choice.

NIKKI HALEY: At the time of the debate, we had to take it to where would you support the nominee, and you had to -- in order to get on that debate stage, you said yes.

The RNC is now not the same RNC.

Now it's Trump's daughter-in-law.

KRISTEN WELKER, Moderator, "Meet the Press": So you're no longer bound by that pledge?

NIKKI HALEY: No, I think I will make what decision I want to make, but that's not something I'm thinking about.

LISA DESJARDINS: Her campaign's future and, she says, her party's future, are riding on how well she performs on Super Tuesday.

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