CHARLESTON, S.C. — “It will be really refreshing to talk about the future,” former Vice President Joe Biden quipped as he took the stage at the International Longshoreman’s Association Hall here on a late Sunday afternoon in July, throwing in a phrase he said his father often used: “Don’t compare me to the Almighty — compare me to the alternative.”

It was Biden’s second day campaigning in the Palmetto State, where he offered apologies for the first time for his warm comments about working with segregationist senators, following public pressure on that front from other presidential candidates such as Sen. Cory Booker, D-N.J., and Sen. Kamala Harris, D-Calif.

The events, including a stop at a local church, marked his foray into the trail in this critical early voting state, where black voters are crucial, after last month's Democratic debate — particularly Harris’ pointed and personal broadside on his 1970s stance on busing — appeared to mark a new phase in what had been a fairly comfortable campaign season for Biden.

Post-debate polls have flashed warning signs for the front-runner. A Reuters/Ipsos poll suggested his support among black voters had dropped by half, while a Quinnipiac poll showed Biden and Harris in a virtual tie after a dramatic shift in black support.

Riding high off her debate performance, Harris announced she would return to South Carolina this weekend; so did Biden. A majority of South Carolina’s primary electorate is black, and Biden’s weekend visit served as an olive branch to black voters and an opportunity to explain his record on race and reset his campaign.

Biden cannot afford to underperform here.

“South Carolina is important because it has a significant African American population, and it can signal which candidates are most appealing to African Americans and Southern Democrats,” Danielle Vinson, a political science professor at Furman University in Greenville, South Carolina, said. “Given how much of a head start [Biden] has in the state with name recognition and goodwill from voters who tend to be more moderate Democrats, if he can’t win here, it will seriously undermine his chances of winning the nomination.”

But despite national survey warning signs, South Carolina party leaders said it would take much more than just a bad debate moment to corrode Biden’s long-standing support with voters here.

“[The debate] is largely a media narrative,” state Sen. Marlon Kimpson said in a phone interview with NBC News. Kimpson hosted the Charleston town hall with Biden on Sunday, as he has done for other top-tier primary candidates. “No one I talk to thinks busing is an issue.”

“Do not fall prey to anyone’s attempt to manufacture a fight to drive media attention,” Kimpson later said as he introduced Biden at the town hall. “I do not find it useful to relitigate issues from 1950, or 50 years ago, or 25 years ago. I have very little particular use for that kind of analysis.”

As voters waited outside the town hall in the sweltering July heat, many echoed Kimpson's views.

“It didn’t really stick with me, because I get it,” Virginia King, a Charleston resident, said of the recent attacks against Biden’s civil rights record, including the issue of busing. “I get what he did and when he did it. I don’t hold those things against him. They were different times,” she said, before emphasizing the importance of beating President Donald Trump.

Ransom Hugh, a retiree from the Charleston area, was critical of Harris' approach during the debate, saying her attack made him sympathize with Biden.

“That was really inappropriate from my point of view. We’re talking about now, not then,” Hugh said. “Biden will restore dignity. We’ve got a clown up in there now.”

Jada Orr, 19, who was back home in Charleston for the summer after finishing her freshman year at Howard University, said that although she was not sold on Biden and was considering other candidates such as Sen. Elizabeth Warren, D-Mass., Harris' debate performance didn’t leave her feeling positively about either candidate.

“Every election, there is an emphasis on the black vote. I want to see how genuine candidates are about coming here and about winning our vote,” Orr commented, as she waited for Biden in an overflow room adjacent to the union hall. “How genuine they are matters. I am not sure about Kamala Harris right now ... But it kind of bothered me that within minutes [of the debate], her campaign posted pictures of her as a little girl and was selling T-shirts. It rubbed some people here the wrong way.”

Biden himself balanced regret with defiance — and expressed confidence black voters here would give him the benefit of the doubt on the recent controversies over his record. "I'm proud of my past," he told reporters in Charleston, when asked about pushback over his positive comments about working with segregationist senators. "Have I made mistakes? Yes. Do we grow? Yes."

"But the fact of the matter is, that's why I chose [to speak] here in South Carolina," he added. "And chose an audience that, in fact, would be the most likely to have been offended by anything that was said."

Party leaders are quick to point out that Biden’s relationships in the state go back decades. His family has long vacationed at Kiawah, just south of Charleston, and his network in the state is strong.

“You can’t underestimate the depth and the width of Biden’s relationship in the state, and sometimes those supersede political moments and political times,” Antjuan Seawright, a South Carolina Democratic political strategist, said.

But nothing is certain. “I don't think he can afford to take anything for granted, or have too many more moments like the debate,” Seawright noted.

Although many Democrats are skeptical of just how much of an impact these past few weeks will have on Biden’s footing among black voters, some say that he might have reason to worry. His support is strongest among older black voters who frequently say their top priority is beating Trump. If they can be convinced that another candidate is just as — or more — electable than Biden, observers say, he could begin hemorrhaging supporters.

“Rank-and-file Democratic voters have shown themselves to be very pragmatic thus far,” Joel Payne, a Democratic strategist, said. “Biden’s issue now is that his assumption of electability was greatly damaged during the debate last week.”

The mission for Biden, whose early support in South Carolina looks a lot like Hillary Clinton’s in 2008, is simple: avoid her fate that year. Clinton, who was seen as the safe choice, dominated early polls, especially among black voters. But after Barack Obama's Iowa caucuses win proved he could win white voters and negated Clinton’s perceived advantage in electability argument, many of those voters rethought their vote. She later lost South Carolina decisively.

Still, as Seawright and others argue, the political climate in 2020 is very different than 2008. That could work in Biden’s favor.

“We did not have Donald Trump in the White House going into the 2008 primary. The mood of the party, the mood of the country is different,” Seawright, who worked for Clinton in 2008, said. “The fact of the matter is that the urgency for this party to be united and less divided is greater now than it was in 2008. We definitely can’t afford to go into this general election, even more so than 2008, with deep and severe cuts and bruises.”