GREENVILLE, S.C. — Sen. Marco Rubio has no obvious, singular base of support for his presidential campaign. He is not running to be the favorite of social conservatives, as Mike Huckabee or Ted Cruz are. He is not aiming to be the most determined national security hawk, as Lindsey Graham is. And he does not have the Republican establishment roots that come with the Bush family name.
But if there is one group that encapsulates what the Rubio base is, it would probably be the Republican voters of South Carolina. The electorate here, with its close replication of all three legs of the Republican Party's stool of fiscal, social and national defense conservatives, essentially fits the Rubio campaign's playbook.
Rubio spent the last two days testing the waters here as he made a relatively quiet trip through the central and northeastern parts of the state, drawing curious but not especially large crowds. His approach at this point — seven months before the first voting starts — is to keep his profile and the expectations around his campaign low, but not so low that he fades into the background of a noisy 16-person field.
The role of the underdog is one that Rubio has played well before — early on in his bids for local office in West Miami and later as a long-shot candidate for U.S. Senate. And it is one that his admirers in South Carolina believe will serve him well when the state holds the nation's second primary, on Feb. 20.
"The state fits his natural strengths," said Matt Moore, the chairman of the South Carolina Republican Party, who says he is neutral in the race but considers Rubio a friend.
Moore pointed to the state's recent history of electing Republicans who started out low profile, like Nikki Haley, the governor, and Tim Scott, its junior senator. He said that reminded him of how Rubio had always operated.
"They're running a lean, mean, almost a startup campaign," Moore added. "They're agile. They relish the role of underdog, and those are the campaigns that have been successful."
Rubio's campaign team and the super PAC supporting him are heavy on South Carolina talent. His campaign manager, Terry Sullivan, ran Mitt Romney's 2008 operation in the state. Sullivan also worked as the campaign manager for Jim DeMint, a former senator from South Carolina who now leads the Heritage Foundation.
The super PAC supporting him, Conservative Solutions PAC, is based in the state's capital, Columbia, and is run by J. Warren Tompkins, a veteran of state politics.
"In South Carolina, because of the complexion of the primary electorate, he is positioned across all segments," Tompkins said of Rubio. "He is very clearly on the right side of foreign policy and national defense. He is very clearly right on the issues of social conservative voters and family issues. And he is definitely in line with the economic conservatives of South Carolina."
As he spoke to voters here on Monday and Tuesday, Rubio tried to appeal to all three sides.
"Today, we're losing our edge," he told a crowd gathered at a CrossFit gym outside downtown Greenville, "because we regulate and try to regulate every aspect of our economy as if it were still 1995."
Drawing some of the loudest applause of the night, he later told the crowd, "When I'm president of the United States, we're going to have a Supreme Court, and we're going to have an attorney general, that defends the right of every American to live out the teachings of their faith and their traditional values at home, at work and in their business."
And in an appearance hosted by Americans for Peace, Prosperity and Security on Tuesday morning, he promised to double down on sanctions against Iran if elected president, declaring, "They can have an economy, or they can have a nuclear weapons program. But they cannot have both."
The under-the-radar path Rubio has taken lately — showing that he is content to let Huckabee and others make provocative comments in what appears to be a contest to grab the oxygen being consumed by Donald J. Trump — did not go unnoticed here.
"He doesn't do stupid things to get his name out there," said Jessica Doscher, 20, who is to be a junior at Winthrop University in the fall. Doscher listed many of the characteristics that other Rubio supporters said they found attractive: the senator's working-class, immigrant upbringing; his potential to rebuild the Republican Party's relationship with Hispanics; his nonconfrontational approach to politics.
But like many in the crowds that greeted Rubio, she said it was too early to have her mind made up. "I think he's one of the better candidates for the Republican Party," she went on. "He's got a sense of awareness and competence and patience that a lot of them don't. A lot of the candidates are reactionary. He's not."
Sally Long, a retired Caterpillar employee from Greenville who watched Rubio speak Monday night, approached the senator after his remarks, leaned into him and said in a soft voice: "Be strong. We're for you."
Long, 62, said the idea of voting for a Republican who is not like her — older and white — was appealing. "I like someone with a broader spectrum and a background that isn't like mine at all," she said. "He can speak to people I can't speak to — and I suspect people that Jeb and Hillary can't speak to, either."
At some point, though, Rubio will need to break out.
Mikee Johnson, the chairman of the South Carolina Chamber of Commerce, told what he said was an instructive story about the state of the race. Johnson said that when he donated blood the other day, he asked the clinicians if they knew who was running for president. "They could name three names: Bush, Trump and Hillary. There's something to be said for that," he said, before adding, "But it's early."