‘Rick Santorum has never been considered a go-to guy for Big Business on Capitol Hill. After all, some corporate types are nervous about his blue-collar roots, his populist proclivities, and his emphasis on religious issues.” So began a Business Week story in January 2006. At the time, Santorum was scrambling to raise money for his reelection campaign against Democrat Bob Casey, a race he ultimately lost. Six years later, however, the perception persists. And at least one corporate type — Mitt Romney — is nervous about Santorum’s rising Rust Belt appeal.

According to the latest polls, Santorum continues to surge in recession-plagued Michigan, which will hold its primary in late February. In the Great Lakes State’s factory towns, where closed auto plants and shuttered strip-mall stores dot the landscape, Santorum’s gritty, middle-class rhetoric is resonating. An American Research Group poll of likely Republican voters has Santorum up by six points, 33 percent to Romney’s 27 percent. A Public Policy Polling survey shows an even larger margin: Santorum leads Romney by 15 points, 39 percent to 24 percent.

Sensing danger, Romney’s campaign has launched a new ad on the Michigan airwaves, touting Romney’s childhood in Detroit, where he grew up as the son of a popular governor. But as they eye the front-runner’s maneuvers, several Santorum advisers tell National Review Online that if Romney’s strategy is to remind people that he used to live in the state, then they’re confident about their chances there. As evidence, they point to the PPP poll, in which a majority of respondents told pollster Tom Jensen that they don’t consider Romney to be a Michigander.

Indeed, if the polling is right and Romney’s home-field advantage is largely superficial, then Santorum’s team sees a real opening to make the Michigan primary a messaging battle. It will partly be a matter of optics — a Pennsylvanian in a sweater vest versus a Bain executive. But at the heart of the pitch will be a policy contrast. On that front, Santorum aides are readying a final, two-week push to illustrate Santorum’s economic populism. There will be mailings and radio spots about his blue-collar beliefs. Unlike his rivals, he’ll talk about incentivizing American companies.

On Thursday, Santorum will address a group of local business leaders at the Detroit Economic Club. Expect him to add policy specifics to his stump speech’s broader themes, a task he has largely avoided thus far. He’ll carefully explain his proposed overhaul, which would create two income tax rates — 10 percent and 28 percent. And he will promote his plan’s tax breaks, which are designed to appeal to conservative parents in Cheboygan and Flint. That includes eliminating the corporate tax for manufacturers and tripling the personal deduction for each child in a family.

“They’ve been looking forward to this speech for months,” says one source close to Santorum’s senior team. “Michigan has always been seen as potential Santorum territory, as a place where they could surprise. Going to Detroit, with all of its manufacturing history, is easy for Santorum. He wants to bring this back to jobs. I know they’re planning on expanding [the platform].”

Some conservatives criticize Santorum’s tax plan for favoring certain constituencies, calling it a pander to frustrated voters in Michigan and the broader industrial Rust Belt. “Cleaning up the tax code and broadening the tax code is not easy to tackle politically,” says Alex Brill, an economist at the American Enterprise Institute. “At the moment, it’s not just that the rates are too high, it’s that there are too many goodies in the existing system. Santorum’s plan doesn’t address that; it’s quite the opposite.”

But Santorum’s advisers say the former senator is committed to the sweeteners, and argue that, even if you disagree with his exemptions, you can’t forget that he’d collapse the tax code from six brackets to two. They also point out that tax incentives may not make supply-siders swoon, but they do reinforce Santorum’s passionate commitment to working men and women, especially as the race heads to Michigan and to Ohio on March 6. “It’s the paycheck-to-paycheck folks, they want to hear someone talk directly to them,” says Chuck Laudner, a Republican operative who managed Santorum’s victories in the Iowa and Minnesota caucuses.

“With Santorum, people realize that this is not about platitudes and talking points,” Laudner says. “This is about conviction, trust, and a little fight. He is going to continue to speak directly to the working class, the blue-collar people, and relate.” In Detroit, “he’ll come armed with solutions, with ideas about how to get things moving again.” The speech, he predicts, will be right in Santorum’s “wheelhouse,” with frank discussion about “how to make us competitive.”

In a background conversation, another Santorum campaign source observes that Thursday’s speech is important as the campaign drives its message in Michigan. But the source takes care to say that the speech will not be a “must-impress moment” akin to Romney’s recent address to the Conservative Political Action Conference in Washington, in which the former Massachusetts governor attempted to assure skeptical conservatives of his credentials. “This will be a dive into the weeds on policy, not a ‘scared at CPAC’ sort of thing,” the source says. “We’re in a strong position.”

Most of that strength, in the polls and in the message, comes from the candidate, aides say. Former staffers corroborate that assessment. According to Seth Leibsohn, who served as an early policy adviser to Santorum, the senator has been focused on manufacturing since he jumped into the race. “Since he has been at one percent in the polls,” Leibsohn chuckles.

“We spent a long time discussing his economic agenda; we went back and forth for weeks, looking at a lot of different plans,” Leibsohn says. “But [Santorum] quickly settled on these ideas, the focus on manufacturing. I told him that the Wall Street Journal wouldn’t like it. He said that he knew they wouldn’t like it but he didn’t care.” Santorum wanted to connect with people affected by the economic downturn, Leibsohn adds, “to tell them that we won’t wash our hands of them. It was his top priority and he reiterated that to all of us on every conference call.”

Months later, now at the top of the polls, Santorum continues to make that case. It worked for him in the small towns near the Iowa cornfields, and in Missouri, Minnesota, and Colorado. His campaign is betting that, in a couple of weeks, it will lead to another Midwestern stunner.

— Robert Costa is a political reporter for National Review.