Rick’s Roll

Since the start of the Republican presidential campaign, eight major candidates have auditioned for the part of Mitt Romney’s foil. Rick Santorum was the last to get a long look. The former Pennsylvania Senator lacks Michele Bachmann’s Tea Party zeal, Rick Perry’s swagger, Herman Cain’s theatricality and Newt Gingrich’s gift for the crowd-rousing zinger. When Santorum won the Iowa caucuses in January, his success seemed as if it might be a fleeting tribute to his huge investment of time in the state. Even as he held a victory bash at a cramped suburban Des Moines hotel with a bear pelt hanging over the doorway, skeptics predicted he would become the latest in a procession of pretenders to fizzle after catching fire. And he did.

In a primary season packed with suspense, Santorum’s improbable resurgence is the biggest twist yet. At a moment when Romney’s grip on the GOP appears more tenuous than ever, Santorum is looking to rewrite the story of Romney’s inevitable coronation. Santorum has captured conservatives, Tea Partyers and Evangelicals, and with Gingrich stuck in a tailspin, he may finally be unifying the fractious factions of the party’s base. Santorum is even leading in Romney’s native state of Michigan, where Republicans will vote on Feb. 28 and where a defeat would devastate Romney. With Super Tuesday a week later, the GOP race would, in a sense, start all over again.

From the beginning, Santorum was the sleeper threat. He employs no pollster. To patch holes in his threadbare campaign, he relies on volunteers to help orchestrate rallies or join his traveling entourage. During a low point in Florida last month, as Santorum foundered in the polls and struggled to attract media attention, his aides asked a reporter to forward around an invitation to travel with the candidate. And then there’s money: in the two months before his Feb. 7 sweep of Missouri, Minnesota and Colorado, Santorum and his outside allies were outspent on television advertising 10 to 1 by Romney’s forces, according to data compiled for the Washington Post.

At the same time, Santorum’s underdog status and accessible manner can be assets. On the trail, Santorum prefers a freewheeling give-and-take with voters to a choreographed photo op. He frequently spars with hecklers. He has endeared himself to fans with his fondness for sweater-vests. And while he’s not so good at concealing his irritation–Cain once described Santorum as “stressed”–he almost always engages on a tough question. “He has a boundless energy, starting each morning with 50 push-ups,” says Foster Friess, the Wyoming millionaire who has been a major donor to Santorum’s super PAC. “I remember one night finishing up our tour of town-hall meetings after 9:00 p.m., when I’m ready to fall into bed, and he’s getting ready to take his family out to dinner at the nearby Denny’s.”

Republicans may also be responding to his substantive differences with Romney. From abortion to gay marriage, Santorum checks nearly every box a social conservative would want and without Romney’s many past reversals. A recent shift in the political conversation to social issues like contraception and abortion may be reminding Republicans that they want more than an accomplished businessman in the White House. Many Republicans see Santorum as a genuine conservative and Romney as a moderate technocrat who simply poses as one. And Santorum’s emphasis on manufacturing both appeals to blue collar workers and helps remind voters that Romney is no working-class hero.

Those factors have given Santorum a chance to humiliate Romney in a state that should be a fire wall. Romney grew up in Michigan, where his family was political royalty. His father was a famed auto-company executive, served as governor in the 1960s and ran for President. Santorum allies salivate at the prospect of an upset. “That giant sucking sound would be the life coming out of the Romney campaign,” says Stuart Roy, an adviser to the Red, White and Blue Fund, a pro-Santorum super PAC. That’s not just bluster. Representative Bill Huizenga, a Michigan Republican who backs Romney, said a defeat in his state would be “a huge embarrassment” for Romney.

With expectations running high, however, a Michigan flop could also pop Santorum’s bubble. Though he is the toast of the Tea Party right now, Santorum is in some ways the unlikeliest of the anti-Mitts. He spent 16 years in Congress and worked closely with K Street lobbyists. Defending his Senate seat in a purple-to-blue state, he often bucked conservative doctrine, voting for earmarks and spending bills and against a national “right to work” act. (It still didn’t save him from an 18-point defeat in 2006.) Until now, Santorum has largely flown under the radar of the Romney campaign’s onslaughts, which blew Gingrich out of the sky. Santorum has enjoyed the luxury of introducing himself on his own terms. But that is about to change.

Rust Belt Battle

As the Romney attack machine rumbles to life, Santorum is preparing an offensive of his own. Stuck to the office wall of his top strategist, John Brabender, is a sea of yellow Post-it notes that form a makeshift blueprint for maximizing the campaign’s modest resources. In the wake of his Feb. 7 victories, Santorum netted more than $1 million, mostly from small-dollar donors, on each of three consecutive days, with each day’s haul more than his total last fall. With a skimpy war chest, winning requires a political version of Moneyball, so Santorum has learned how to hunt delegates at a discount. “I’m willing to concede today that if this race is about who can run the most negative ads, we can all get out now and declare Romney the winner,” Brabender says. “Gingrich probably made a tragic mistake when he bet the ranch on Florida and lost. We’re not going to make that mistake.”

Instead Brabender is surveying the electoral landscape for ways to vacuum up votes on the cheap. A knockout in Michigan isn’t the only path to victory. Santorum’s team is focusing on conservative states that award delegates proportionally, rewarding a second- or even third-place finisher, and have inexpensive media markets. The strategy has already borne fruit. While Romney and Gingrich dueled in Florida, Santorum barnstormed Minnesota, Missouri and Colorado and snatched race-changing wins in states no one else had considered worth the fight. Now his aides are targeting March 6 Super Tuesday contests in Georgia, Oklahoma, North Dakota, Tennessee and Idaho as chances to win delegates on the cheap, as well as Ohio, another ailing Rust Belt state where Santorum’s profile might trump Romney’s.

That’s why Romney would love to dispatch Santorum in Michigan. Romney won the state comfortably in 2008, and as a self-styled “son of Detroit,” he may have expected another cakewalk this time around. Yet he lags Santorum by an average of 9 points in recent polls. Those numbers were disquieting enough to make Romney dump $1.2 million into advertising in Michigan, including a spot that highlights his local roots with sepia-toned family footage. A rather less sentimental campaign, funded by Romney’s deep-pocketed super PAC, flays Santorum as a “Washington insider” and “big spender” who voted repeatedly to raise the federal debt limit. In response, Santorum, who has spent a fraction as much, unveiled an ad branding Romney a nasty, machine-gunning “Rombo.” Keenly aware that Romney’s unfavorability ratings have spiked in recent weeks, the Santorum camp hopes to provoke a backlash against his negative attacks.

Santorum also aims to drive home doubts about Romney’s ability to connect with average Americans. In a recession-racked industrial state like Michigan, Santorum’s blue collar biography–his grandfather emigrated from Italy to work in the coal mines of southwestern Pennsylvania; both his parents were devout Catholics who worked at a local Veteran’s Administration hospital–stands in sharp contrast to Romney’s tin-eared affluence. “How many times have you heard that Romney looks and acts like a President from central casting? Yet at the same time, people have a problem relating to him,” Brabender says.

One way to build such a bond is through a candidate’s economic platform. Santorum proposes to eliminate taxes on the manufacturing sector, including taxes on companies repatriating business from overseas. He would halve the corporate tax rate to 17.5%, a deeper whack than Romney’s proposed rate of 25%. (One fortunate fact for Romney’s Michigan prospects: Santorum, like Romney, opposed the Obama Administration’s auto-industry bailouts.)

Finally, Santorum might clean up among fellow Catholics, who make up some 30% of the GOP electorate in Michigan. Social issues could prove especially potent as the political storm over the Obama Administration’s ruling requiring religious organizations to cover contraception in their health plans calls up memories of Romney’s pro-choice past.

Presidential Material?

Social issues can cut both ways, however. Santorum’s edge over Romney among social conservatives helps explain why plenty of GOP insiders fear that he is the much weaker threat to President Obama. In a 2005 book, Santorum suggested that “radical feminists” had led more women to join the workforce, something many Americans hardly consider a social crisis. He has opposed allowing a greater role for women in military combat. And in an interview he gave to an Evangelical blog last October, Santorum called contraception “not okay” and “a license to do things in the sexual realm that is counter to how things are supposed to be.” Romney isn’t likely to attack Santorum from the left himself, but his supporters are sure to publicize positions like these.

There’s also the question of stature. Santorum’s advisers concede that his everyman style doesn’t fit the Hollywood image of a President quite the way Romney does. If the jut-jawed Romney screams CEO, Santorum has a middle-management way about him. But Santorum’s advisers believe that in this anti-elite moment, a little populism can go a long way. “We make fun of the sweater vest,” Brabender adds, “but there is a metaphor there that matters.”

And nothing builds stature like success. If Santorum can withstand Romney’s attacks in a way that Gingrich could not, he’ll quickly earn more respect from skeptical Republicans. In the end, that is the benchmark he must meet to convince GOP voters that he is a viable champion. Not being Mitt Romney is not going to be enough.

Some Republicans are already wondering whether Santorum might be a stronger general-election candidate than they’d assumed. Appeal to blue collar Catholics is quite an asset in a presidential election. It’s one reason Obama chose Joe Biden as his running mate.

TO SEE POLITICAL FASHION STATEMENTS, GO TO TIME.COM/SWEATERVESTS