Made wealthy by decades in the cutthroat trenches of venture capital, Bruce Rauner has never been shy about opening up his checkbook to push causes he considers dear to his heart.

Dartmouth College, his alma mater, has Rauner scholarships, a Rauner dormitory, a Bruce V. Rauner endowed professor of economics and a Rauner Special Collections Library, bankrolled over the years with millions of dollars in gifts from the now Republican governor hopeful.

In Chicago, there's a neighborhood YMCA, a Red Cross headquarters and a charter high school that also bear Rauner's name, again a testament to a wide open checkbook.

Now Rauner is spending even more of a personal fortune he pegs at more than $500 million in an attempt to make his biggest and most personal impact yet on the public stage.

The opinionated, supremely confident salesman of his own brand has skillfully leveraged those assets to make critical business and social connections and wield influence on school policy at Chicago's City Hall. Now he has launched a political career from scratch that has seen him quickly become the front-runner in the March 18 primary election.

"I'm a successful guy at everything I've done," said the 58-year-old from Winnetka in a recent interview. "I've kicked tails. I've gotten results. I could go do a hundred other things. I love this state. This is about protecting our home. No one else is going to do it. I'll do it."

Critics of Rauner voice their disdain in equally forceful measure.

Karen Lewis, president of the Chicago Teachers Union on which Rauner frequently heaps scorn, sees him as driven by intolerant bluster and an abiding hate of organized labor. "He sounds like he's running for emperor, not governor," said Lewis, who led a seven-day Chicago teacher's strike in 2012 that Rauner played a behind-the-scenes role in provoking.

All of which is to underscore how there is little subtle about Rauner: from his array of luxury homes; to the millions he donates to push charter schools; to slash-and-burn accusations that rivals take campaign cash "bribes"; to a booming bass voice and a 6-foot-4-inch frame that literally rises over the four-man field in the GOP governor's contest.

At its core, however, the story of Rauner's first-ever run for public office is a testament to his skill at making and spending his money.

Rauner is tapping his own deep pockets and those of powerful friends in corporate suites to construct a fundraising juggernaut he has used to saturate the airwaves with campaign ads.

He has donated $6 million of his own money to his campaign, nearly three times the total raised by all three of his rivals combined, and an Illinois record for a candidate's self-financing in a primary race for governor. On top of that, Rauner has raised about $8 million in individual donations, much of it in six-figure amounts from leaders of investment firms with stakes in an array of businesses.

Yet Rauner says he is confident those donations will have no influence on his decisions as governor, even as he contends rivals are deeply compromised for taking union contributions.

Rauner argues he is too wealthy to be for sale. "I have an agenda and I've laid it out, and it's not about special deals," he said. "That's what politicians do. I am not a politician."

Such tough talk sells well with Republican audiences tilting ever more to the right, but it's unclear how it might play more broadly in a deep blue state should Rauner gain the GOP nomination and take on incumbent Democrat Pat Quinn in November.

In 2012, voters soundly rejected the presidential bid of Republican Mitt Romney, who also made his fortune running a venture capital empire, drew core support from a wealthy investor class and owned an array of opulent homes.

Rauner dismisses Romney analogies. "He came across as a blue blood," said Rauner, who insists he is anything but. "I'm a regular guy. I drink beer. I don't drink Courvoisier or whatever the hell that stuff is. I drink beer and I smoke a cigar and I ride a Harley and I love to fish."

The regular guy imagery is front and center in Rauner's campaign, which portrays the candidate as a kind of Joe the Plumber of multimillionaires.

As a symbol of frugality, Rauner highlights his $18 wristwatch, apparently a cheaper model than the $34 timepiece he wore when the Tribune profiled him in 2003.

On the stump, Rauner also talks up his modest upbringing, relating a sometimes incomplete biography. He reminisces about growing up in a small Deerfield ranch house, not mentioning that parts of his youth were also spent in upscale Lake Forest as well as Scottsdale, Ariz.