FORT MILL, S.C. — The first Jaime Harrison signs began appearing in front yards here over the summer, then multiplied as more residents of this heavily White, conservative suburb proudly proclaimed their support for the Black Democrat running for U.S. Senate.

“Is this really happening here?” said Bethany Pierce, 40, a librarian who has been a part of a wave of Democrats who have recently moved from nearby Charlotte.

In another Republican stronghold, two hours west in the foothills of the Blue Ridge Mountains, some say they feel betrayed by Sen. Lindsey O. Graham, the Republican incumbent who four years ago called Donald Trump a “kook” but has spent much of his time ever since cozying up to him.

“Lindsey seems to have lost the spirit of service to his constituents,” said Casey Farra, 45, a former microbiologist and a Republican. “Jaime seems like a man of faith and truth.”

And in Charleston, home to one of the state’s largest Black communities, African American voters who put former vice president Joe Biden on the path to the Democratic presidential nomination are starting to think they can rock national politics again by turning out to send one of their own to Washington.

“This state, this whole country, is ready for change,” said Dianne Nelson, a 65-year-old retired nurse.

With much of the country grappling with the role of race in society, the 44-year-old Harrison is placing a political bet that once seemed unthinkable but now feels plausible: that South Carolina, where the Confederate flag flew on the State House grounds until 2015, could become the first in the country to send two African Americans to the U.S. Senate. Sen. Tim Scott, a Republican who is not up for reelection, is the other.

Although Harrison’s name might be new to the national stage, he is certainly not new to Washington politics. A protege of Rep. James E. Clyburn (D-S.C.) and a former chair of the state Democratic Party, he has spent much of the past 20 years forging political relationships and building up a political infrastructure for the left in South Carolina.

He’s been able to leverage those relationships to help produce record-shattering fundraising numbers in an effort to take on one of the most polarizing politicians in Washington.

Central to Harrison’s wager is that the same state that elected vocal segregationists to hold the very seat he is seeking, the seat now held by one of President Trump’s most prominent defenders, is prepared to take its place as a trendsetter in a changing South. And he is making race a central element of his closing argument.

“The South is transforming,” Harrison said in an interview. “And what we are seeing is the emergence of what I call the ‘New South,’ one that is bold, inclusive and diverse.”

Harrison, who was born to a poor teenage mother in rural Orangeburg and went on to graduate from Yale University and Georgetown Law, tells crowds at drive-in rallies that his election would be a potential “bookend” for South Carolina, ending its reputation as the first to secede during the Civil War and embracing the values of a rapidly transforming state.

“This was the seat of Ben ‘Pitchfork’ Tillman, who would go to the floor of the U.S. Senate and talk about the joys of lynching Black folks,” Harrison said at a recent rally, pledging that this year the state’s voters would “close the book on the Old South.”

Only five states are growing faster than South Carolina — and more than 560,000 have registered to vote here since 2016.

The state does not have partisan registration, but Democrats are looking to pick up support from a mix of retirees from the Northeast; African Americans from the Midwest returning to their roots; young professionals taking jobs in the automotive and aviation manufacturing industries; and liberal North Carolinians who have crossed the border in search of bigger houses and better schools.

Harrison told The Washington Post that he hopes that those newcomers, joining in with traditional Democrats, and the broad distaste among suburban women for Trump’s antics will enable him to build on the momentum of former candidates such as Stacey Abrams in Georgia, Beto O’Rourke in Texas and Andrew Gillum in Florida — who ran closer-than-expected statewide races in 2018 but fell short.

Harrison thinks he will fare better because he is running against Graham, a man who Harrison says traded his bipartisan instincts for fealty to a polarizing president.

Harrison’s prime example has been Graham’s staunch support of Amy Coney Barrett’s Supreme Court nomination after he vowed he would never support a justice’s confirmation in a presidential election year.

“Use my words against me,” Graham famously instructed voters to do if he changed his mind about court nominations. Harrison does.

“He is the thing that [voters] hate most about politics: someone who can’t be honest about who they are,” Harrison said. “And then, you get a round-headed, smiley guy like me talking about hope all the time.”

Recent polls have shown the race either tied or with Harrison narrowly trailing, and the nonpartisan Cook Political Report considers it a toss-up.

Graham has warned his base to be wary of Harrison. He argued that Harrison was a typical Democrat who would enable the agenda for the “radical left,” which helps explain how he has drawn so much money from outside groups eager to give Graham the boot. The Lincoln Project — a group of former Republicans bent on taking down Trump and his allies — has been producing blistering commercials against Graham, including one comparing him to a parasite. Meanwhile, Harrison took in a third-quarter haul of $57 million that far eclipsed any Senate candidate in American history.

“Where is the money coming from?” Graham has asked repeatedly, although his campaign is upset with some places where the money is going.

South Carolina Republican officials say that, in the end, conservatives will come home to Graham. What’s more, said state Republican Party Chairman Drew McKissick, those newcomers Harrison is trying to court are actually conservatives who come to the state for low taxes and cheaper homes.

He also says Democrats have made a fatal mistake by reducing door-to-door campaigning as the country faces the coronavirus crisis, leaving an opportunity for Republicans to persuade voters who might be shaky on the senator. “Stop your bellyaching” is McKissick’s message to them. For some, the message seems to be working.

“I have my issues with Lindsey, but we need people that support the president,” Donna Cantrell, 72, said outside the voting booths in Anderson.

“We have to keep that seat,” added her husband, Jerry, also 72, saying he appreciated Trump’s stance on low taxes and immigration. “The Democrats can’t get the Senate.”

On the trail, Harrison tries to speak above the partisan fray and present himself as the embodiment of the American Dream. He references a popular segment cut by professional wrestler Dusty Rhodes about experiencing “hard times,” moments when those in power seem to be working in the interest of themselves while ignoring the pain of others.

He often avoids talking about Trump, but focuses on issues such as the need to expand broadband access in rural areas and to fix an uneven health-care system short on doctors and hospitals.

But his most resonant attacks are about Graham. One of Harrison’s biggest applause lines is a promise of his own.

“I will never lie to you,” Harrison tells them.

Harrison’s “New South” mantra carries echoes of a similar campaign 30 years earlier north of the border, when Harvey Gantt, the Black former mayor of Charlotte burst to national stardom with a well-financed and highly energized bid to oust the conservative icon Sen. Jesse Helms (R-N.C.).

The big question is whether Harrison can overcome the obstacles that blocked Gantt’s path.

Back then, Gantt said, his team believed they could win North Carolina if they garnered 95 percent of the Black vote and a third of the White votes.

The strategy seemed to be working, but Helms pulled away after producing an ad that featured the hands of a White man losing his job to a minority because of racial quotasa reminder that White grievance remained strong in the South.

Now, Gantt, who was born in Charleston, says the race issue might work in Harrison’s favor as the nation seems more interested in elevating the voices of people of color after the death of George Floyd, who was killed in police custody in May. Those efforts seemed particularly resonant in a place like South Carolina, Gantt said, which he said had always had a more independent streak than other parts of the South.

That strain stretches to Gantt’s personal history integrating Clemson University in the early 1960s, when he said local leaders insisted that his presence on campus not draw aggressive protest or resistance. It continued on with the elections of Scott and Nikki Haley — the country’s first Indian American female governor — and was most evident recently when the state legislature found the Confederate flag flying near the State House to be an embarrassment after a white supremacist killed nine people who were praying at Emanuel African Methodist Episcopal Church in Charleston.

“There’s always been an element of decency in South Carolina,” Gantt said. “You can appeal to their manners more than the morality of the issue.”

Still, Scott and Haley were Republicans and, as a longtime political strategist, Harrison knew the path would be harder for Democrats to win a statewide election.

While working as an aide to Clyburn on Capitol Hill in the mid-2000s, Harrison would constantly talk with his friend Clay Middleton, who was also on the Hill, about what it might take for Democrats to gain traction in South Carolina. The two agreed that the state party needed to become more organized, find better candidates and figure out a way to support them.

“I would be lying if I said, when Jaime and I met 20 years ago, we knew this moment was going to happen in our lifetime, when we are in our prime,” said Middleton, now a political operative in the state.

So Harrison started a fellowship program named after Clyburn to introduce college-age residents to the world of politics. He created a local political action committee and asked fellow Democrats to pool $100 a week.

“We don’t have a lot of money, but if we start a PAC, maybe we can make an impact,” recalled Colleen Condon, chair of the Charleston County Democrats.

From 2013 to 2017, Harrison served as the head of the state Democratic Party. They started seeing some small results in Charleston, winning seats at the county level and flipping a congressional seat in 2018 in a district that Trump had previously won by 13 points.

That same year, JA Moore, a chef, had decided that he, too, was going to run for a seat in the State House. He had always loved politics, but he said he felt a new inspiration to do something more consequential after his sister was killed in the shooting at Emanuel African Methodist Episcopal Church.

After the initial enthusiasm of his candidacy, Moore said, he began to question his odds. He was challenging a Black Republican incumbent named Samuel Rivers Jr.

“Jaime didn’t do a ‘Yes, we can speech’ or anything, but he was so supportive,” Moore said. “He said you’ll be able to get some Black votes and some Republican votes. And you’ll get some progressives and Latinos and women. He wouldn’t let me doubt myself. He told me to just keep telling my story.”

Moore ended up winning the race by five points.

Two years later, Harrison was employing the same strategy for himself. Harrison told The Post that his first step was to try to up his name recognition in the state. As money started to flow, he increased his campaign’s paid staff from two to 52. They put his name up on billboards and street corners, they plastered his name on tip-calculator apps for cellphones and purchased commercials to play at gas stations.

And then, an incessant number of commercials. As of the third quarter, the campaign had spent $34 million on television ads, $8 million on digital ads, and $2.2 million specifically geared toward Black radio stations.

“The more I could tell my story, the more that my name ID increased, the closer the numbers became,” Harrison said.

Harrison’s advertisements rarely mention the fact that he is a Democrat. Instead, they center on his love of state and country, and his background.

“At first he seemed a little soft to me,” said Marvel Cheeks, a 67-year-old retired political strategist who moved to Anderson, S.C., after years working in the brass-knuckle politics of Detroit. “But that’s what you have to be here in South Carolina if you’re a Black man. They don’t want fire. I came to see that he was playing it right.”

Harrison said he tries to reflect the state’s values when addressing people: firm, hopeful, affable.

His approach worked on Brandon Johnson, 34, a pro-gun, pro-marijuana libertarian who had been so turned off by the antics of Trump and Biden that he planned on voting for a third-party candidate named Jo Jorgensen, but found Harrison’s strategy appealing.

“He seems like a sincere guy, unlike Lindsey Graham, who is a puppet for Trump,” said Johnson, who lives in Rock Hill. “I like him, I don’t know if anyone else will. This is South Carolina, and he’s still a Black man.”

But as Amy Hayes sat outside with two friends on a recent day, she said she felt the culture of the place was indeed changing. In the 15 years that Hayes has lived in the area, she said other members of the local Democratic club had supposed there had to be women in the affluent suburbs nearby who would vote for Democrats.

Hayes said she tried attending local card games and wine nights, hoping to chat politics. It never seemed to work. Then, after 2016, she said women’s groups started popping up in surrounding York County, in neighborhoods where Hayes used to be hesitant to send Black volunteers to go door-knocking. They were closely following the news, attending marches and protesting outside Graham’s office.

“[Members of the party and I] used to talk about whether there would be enough White people to vote for Jaime,” she said to her friend, Susan Demchak, a doctor whose slow retreat from the Republican Party started during the 2008 campaign. “And now our answer is yes, because of people like you.”

“I had to do something,” Demchak said. “I’ll never forget that morning [after the 2016 election]. I went to bed thinking that I was going to wake up in Pantsuit Nation, and I woke up in Planet of the Apes!”

They had both been Graham supporters, even Hayes, a longtime Democrat.

“I thought he would be our hero,” Hayes said.

“A statesman,” Demchak said.

“A check on Trump,” Hayes said.

Those interests now extended beyond electoral politics. NaTasha McNeil, a Rock Hill native who had traveled the world to sing opera and then moved back home to raise her children with her husband, said she found the area to be more open-minded, more inclusive.

For example, this summer, McNeil decided she would contact some local mother’s groups to see if they could find ways to raise their children to be anti-racist. She expected maybe 30 mothers to be interested.

In York County, about five dozen women have been meeting to have their children write letters about their friends, asking police not to hurt them if they ever see them on the street. The women strategize about how they can get the local Confederate Park renamed. And they talk about Harrison.

McNeil, who is African American, knew South Carolina’s political leaning would not change overnight. Signs for Trump and Graham still overwhelm the county, but she said Democrats are waking up.

“So, for the first time in my life, I’m starting to feel more confident that someone like Jaime Harrison could win South Carolina,” McNeil said. “We are the tortoise, but we are still in the race.”

Anu Naryanswamy, Lenny Bronner and Alice Crites contributed to this report.