It’s lunchtime in Sioux City, Iowa. In the Clarion Hotel ballroom, Mitt Romney is preaching his business experience to a couple hundred Republicans who have come to meet the former Massachusetts governor. “I spent my life in the private sector,” he tells the audience as they tuck into ham and turkey sandwiches. “In business, you make a better product or you go out of business. In government, things seem to stay the same.”

Later, as we drive through the Iowa cornfields, Romney continues the sermon, likening being president to being a C.E.O. “If you think about the government of the United States, it is an enterprise. It has leaders, employees,” he declares.

Willard Mitt Romney knows that the urge to have someone run the country like a business is a strong one in American politics. Periodically, this yearning attaches itself to a nutty object of desire. Lee Iacocca was one such love interest, talked up for the White House in the ’80s. That he’s once again made the bestseller list, almost three decades after the historic accomplishment of ­accepting a federal bailout for Chrysler, tells us that we’ll adhere this yearning to any C.E.O. with West Wing swagger. In the ’90s, Ross Perot got a fifth of the vote even though he was, um, odd. ­Today, ­Michael Bloomberg has the virtue of sanity, but his appeal is the same: He’s the executive who, as one C.E.O. who wants a C.E.O. president tells me, “gets things done … without all the bullshit.”

Romney doesn’t curse, but he’s pitching the same idea, and it has made the one-term governor a first-tier candidate. At 60, he’s got one of the best fundraising networks of any Republican candidate, tapping pals like his former Bain & Co. colleague Meg Whitman. “We need a fabulous leader for this country,” the eBay C.E.O. and Romney finance co-chair tells me. “That’s him.”

Not surprisingly, Romney, the first Mormon with a shot at being the ­Republican nominee, also has the backing of executives who share his faith, ­including Bill Marriott, the hotel magnate and a longtime friend. It was the Salt Lake City Olympics in 2002, though, that made Romney a hero to many Mormons. The global spectacle was a signal moment for a flock once branded as outlaws. When Romney took over the Salt Lake Organizing Committee in 1999, the games were a scandal-plagued fiscal wreck. He made them profitable. Romney’s campaign coffers show him to be the pride of his people, a very white Jackie Robinson.

Romney, as is well known, comes by this business acumen naturally. ­Before becoming Republican governor of Michigan in 1963, his father, George, ran American Motors, giving us small and iconic cars such as the Rambler and coining such phrases as gas-guzzler. The son’s rise as a consultant at Bain & Co. and then his founding of Bain Capital, the private equity giant, are well documented too. What’s less understood is what this background might mean in the Oval Office. How would America be led by its first consultant in chief?

For more than six years, we’ve had a depressing example of an M.B.A. president, but our commander in chief and Romney are very different, even though they were, weirdly, in the same Harvard B-school class. Indeed, Romney tweaks George W. Bush subtly but tellingly when he recalls the Republican scion. “I was living in Belmont with a wife and two kids and going home every night to be with them and do my homework.” He pauses for effect, then laughs and says, “George was at a different phase in his life.” I ask Romney if it’s fair to lump him and Bush together as M.B.A. presidents. Romney casts the query aside: “We’re all different.”

That’s true. Bush and Romney may have learned the same case method, but Dubya was a slacker and boozer while the teetotaling Romney was hyper­accomplished, earning not only an M.B.A. but also a law degree from Harvard. In 1984, while at Bain & Co., Romney was asked by Bill Bain, his mentor and the only boss he’s ever had, to start Bain Capital. While Bush was a mediocre oilman, Romney raised $37 million for Bain Capital’s first fund and built the startup into a firm that now has $40 billion under management.

The differences between Romney and Bush don’t end there. To grasp the deeper contrasts, you have to understand Bain’s culture. Bush is infamous for trusting his gut; Romney is always analytical—the hallmark of the Bain approach to both consulting and private equity. To this day, Romney likes his information “voluminous,” says his campaign manager and gubernatorial chief of staff, Beth Myers. Romney might be a congenial panderer, but he isn’t someone who would look into Vladimir Putin’s soul and pronounce him a friend.

Analysis and debate—these defined Romney’s style at Bain Capital, where he would get together with other pioneers who had made the leap from Bain & Co. Over bagels, they would scrutinize business plans from companies that wanted their cash. “We didn’t know anything about venture capital or hedge funds,” says Eric Kriss, a Bain alumnus and blues pianist who served in Governor Romney’s cabinet. “We knew consulting.” Mark Nunnelly, a Bain managing director, recalls Romney’s collegial style: “You didn’t work for Mitt but with him.”

Even today, Bain Capital’s operations reflect the company’s genesis in consulting. Glenn Hutchins, the titan of Silver Lake, another private equity firm, says he has long admired Romney, calling him an innovator for bringing to private equity the Bain & Co. approach—analyzing a business’s practices, “breaking them into their underlying economic models, and reconstructing the business with a bottom-up analysis.” Hutchins, a Hillary Clinton supporter, doesn’t agree with Romney’s politics but calls him “the real deal.”

Under Romney, Bain Capital provided crucial funding for the Sports Authority and Domino’s Pizza as well as Staples, a deal Romney is especially proud of. In 1984, Staples founder Tom Stemberg went to Romney for financing, showing him data indicating that businesses were spending far more on mundane office supplies than they had calculated. Romney and his team did their own analyses of at least 60 other companies, getting granular with pen and paper-clip budgets before deciding to invest. Today, Stemberg credits Romney with providing the crucial cash that made Staples a category killer. “He saw things others didn’t,” Stemberg says. At times, though, Bain is a political burden for Romney. In 1994, Ted ­Kennedy defeated him when he challenged Kennedy for his U.S. Senate seat, charging that Bain cut good jobs when it took over businesses.

Okay, but does a successful business career equal a good presidency? No. Most presidents have been lawyers, generals, and professional officeholders. Only a few have had big business careers, and this cadre of executives does not exactly inspire confidence. By contrast, the most successful presidents never ran big businesses. Franklin Roosevelt was a mediocre lawyer. Ronald Reagan was a rancher, actor, and union boss. Running a business and running a country are not the same thing.

That doesn’t mean the skills a C.E.O. could bring to the Oval Office are irrelevant, let alone disqualifying. But all those skills we associate with an effective executive—hiring talent, delegating authority, ensuring accountability—could also be associated with someone who has been a mayor, like Rudy Giuliani, or a former cabinet secretary, like Bill Richardson. Do I fear a President Romney? Not after the last four years.

I think the Bain Way—the love of data and vigorous debate—would have helped a President Romney make better decisions about Iraq than his classmate. (Of course, a monkey with a dartboard probably would have fared better.) “I think if you’d had General [Anthony] Zinni”—a war critic—“around the table arguing, it would have made a difference,” Romney tells me. “He’d have said if we’re able to topple Saddam quickly, [we] may end up in a sectarian war.”

The Bain Way certainly helped Romney as governor. Finding budget cuts came naturally to the former consultant. Also, the formulation of Massachusetts’ much-heralded plan for universal health care—which mandates that everyone buy coverage and offers subsidies for those who can’t afford it—was preceded by a Bain-style analysis revealing that the state’s uninsured crisis was less about poverty and more about making carefree young folk buy into the system. But at the same time, Romney was a political novice on Beacon Hill, and he saw his vetoes routinely overridden. Knowing what you can and cannot get through a legislature isn’t something you learn in business, no matter how great you’ve been at corporate turnarounds. When Romney has gone with his gut instead of data—as when he said he would double the capacity of the prison at Guantánamo Bay—he has sounded shrill.

It’s fitting for Romney that the last Massachusetts governor to end up as commander in chief was Calvin Coolidge, who publicly revered business more than any other president. “The man who builds a factory builds a temple,” Coolidge declared in one of his many lavish encomiums to free enterprise. “The man who works there worships there.” Romney, the hero of the Salt Lake Temple, has undoubtedly helped build some great temples of commerce. The church of governance, though, is far harder to lead.