Republican presidential candidate Marco Rubio speaks during a campaign town hall at the Omar Shrine Temple in Mount Pleasant, South Carolina February 17, 2016. (Chris Keane/Reuters)

As Sen. Marco Rubio (R-Fla.) waited to speak under a pavilion shading a friendly crowd from the midday sun, Sen. Tim Scott (R-S.C.) evangelized about economic disparity.

“For the middle class, times haven’t gotten better. The recovery has not reached evvvvverybody in Summerville – can I get an ‘Amen?’” bellowed Scott, who has been campaigning for Rubio all week.

When it was Rubio’s turn, he talked about having to write post-dated checks. Hours earlier, he said Vermont Sen. Bernie Sanders had tapped into a real sentiment and he condemned Hillary Clinton for raking campaign cash from Wall Street. The next day, he started it up again.

As Rubio strives for a top-tier finish in South Carolina’s Republican presidential primary, boosted by an endorsement from Gov. Nikki Haley on Wednesday and surveys showing him inching up on Sen. Ted Cruz for second place, he is campaigning with a populist bent. At a time when Sanders and Donald Trump are riding a wave of discontent to surprising early state wins, Rubio is trying to tap the widespread sense of anxiety that can be felt in states like South Carolina, one of the nation’s poorest.

But he is speaking a different language than Trump and Sanders. Sanders rails against large financial institutions he sees as under-taxed and under-regulated, while Rubio blames “big government” banking restrictions for shortchanging smaller institutions. Trump favors deporting illegal immigrants he has blamed for hurting American job seekers. Rubio does not.

And Rubio, unlike Sanders and Trump, depends heavily on wealthy donors, complicating his message.

At a Wednesday campaign stop in Mount Pleasant, Rubio emphasized his modest upbringing and the financial struggles he experienced as an adult, retelling a story he relayed here in Summerville on Tuesday.

“When Jeanette and I were first married for many years early in our marriage we lived paycheck to paycheck. And I’ve had some people say in the last couple days, ‘Define paycheck to paycheck,’” said Rubio.

So he did: “You write a check on Wednesday but you know direct deposit doesn’t come ‘till Friday, so you date it Saturday.” He added: “I’m not saying I ever did that.”

Central to Rubio’s reasoning for nominating him is his oft-stated belief that he is better-equipped for the general election than any other candidate. He has put his personal story at the forefront of that argument.

In general, Rubio’s holds orthodox Republican views on the financial industry. If he is the nominee, it would set up a major clash of ideas with either Sanders or Clinton.

Rubio blames the “Dodd-Frank” law that tightened regulations on banks for hurting smaller institutions that don’t have the resources to fight the new rules imposed by the legislation. But Sanders – and to a lesser extent Clinton – has pilloried the banks themselves and called for higher taxes on the country’s wealthiest companies.

“What has Bernie Sanders tapped into?” Rubio asked supporters Tuesday in Beaufort. “He’s tapped into the sense in America that the game is rigged. That all the people at the top are winning and everyone else is being left behind. There’s truth to that. Here’s what he misses: You know who’s doing the rigging? The government is doing the rigging.”

On Tuesday and again on Wednesday, Rubio knocked Clinton for accepting contributions from Wall Street bankers — a line of attack Sanders has used against her often in the Democratic presidential primary.

But Rubio has benefitted from wealthy contributors who made a fortune in the financial industry. Billionaire hedge fund manager Paul Singer, for example, is one of his biggest backers.

Asked how to square those two parts of his message that seem to be at odds, Rubio repeated a line he often uses to head off criticism that he is beholden to the interests of his donors: “People donate to my campaign — they buy into my agenda.”

Rubio primarily frames immigration as a national security issue, not an economic one. That separates him from some in the Republican Party who worry about immigrants taking jobs away from Americans.

Scott, the Senate’s only black Republican, has served as Rubio’s warm-up act this week. He introduces Rubio confidently like a public address announcer at a professional sporting event: “Marco Ruuuuuuubio!”

In a brief chat with reporters on Tuesday, he sounded equally self-assured about the economic message Rubio and his team have been spreading across the state this week.

“The reality of it is that the bigger the government, the more complicated the regulatory environment, the harder it is for small business to start,” Scott said. “They don’t start, you don’t hire people, you don’t hire people the unemployment [rate] goes higher.”