Tommy Thompson worked the crowd, almost before he was through the door, shaking hands, slapping backs and calling out reporters from across the room.

The former governor and current U.S. Senate candidate was in Madison to pitch his latest campaign proposal, a GOP-friendly energy plan that ignores wind and electricity in favor of fossil fuels.

During the impromptu press conferences before and after the speech, the "classic" Tommy was as clear as ever: engaging the room and shooting from the hip, with a laugh and a shrug.

Thompson's charm has never been in doubt, but the question emerging in the Senate race is whether that will be enough to overcome a changing perception of the former governor since he left office 12 years ago.

Thompson, 70, is the biggest Republican name in the race to replace retiring Democratic Sen. Herb Kohl. If this election were taking place a decade ago, he would likely win the primary going away.

But the new GOP is a party of strong partisans, where dealmakers like Thompson are no longer in vogue. So, if he is going to win over a new generation of Republican voters, Thompson will have to shake his image as a big-government Republican and Washington insider.

"Is Tommy nimble enough to pivot to the right and position himself as a staunch conservative?" said Charles Franklin, Marquette University Law School political scientist. "That's what we're waiting to see."

A different kind of Republican

To face U.S. Rep Tammy Baldwin, the presumptive Democratic nominee, Thompson will have to defeat former U.S. Rep. Mark Neumann and state Assembly Speaker Jeff Fitzgerald, R-Horicon, both experienced politicians with substantial conservative resumes, and Eric Hovde, a deep-pocketed hedge fund manager and newcomer to politics.

Thompson was elected governor four times, the first in 1986. From the start, his approach was that of a big-tent Republican. Thompson had big ideas and a willingness to make deals to get things done.

Mordecai Lee, a UW-Milwaukee political science professor and former Democratic state lawmaker who served with the former governor, said Thompson believed in using government to achieve conservative goals.

"That is a marked departure from modern Republican dogma," he said. "Now, they want to kill the beast. They believe government is the problem. Compare old Tommy to Sen. Ron Johnson. They are as different as the North and South pole."

During his tenure, Thompson pushed through the costly Welfare-to-Work program, which served as a national model for welfare reform, helped create BadgerCare, allowing low-income families with dependent children to get state-subsidized health care, laid the groundwork for high-speed rail and took over two-thirds of the cost for state education — a move that led local governments to cut property taxes.

Accordingly, during his time in office, state spending exploded, increasing from $5.2 billion in 1988 to $11.3 billion in 2000, according to the Wisconsin Taxpayers Alliance. State spending increased to only $13.6 billion in the 12 years since Thompson left office.

Darrin Schmitz, a consultant for Thompson's Senate campaign, said such a reading of the numbers is misleading, because it counts tax cuts as spending.

Todd Berry, president of the Wisconsin Taxpayers Alliance, said that was a period of rapid growth in the country, and in the state.

"There was a lot of money coming in and everybody, Democrat and Republican, had a lot of fun with it," he said.

Berry also noted that he, and others, warned Thompson that some of his moves — like assuming two-thirds of the school funding — were unsustainable and would leave the state with a huge debt.

"And that's what happened," Berry said. "Scott McCallum came into office and had a billion-dollar debt waiting for him."

Unable to continue footing the bill, then-Gov. Jim Doyle ended the state's two-thirds school funding pledge in 2003.

This kind of a criticism has dogged Thompson. Even before he officially entered the race, the national conservative group Club for Growth, which endorsed Neumann in early September, pushed the notion that Thompson isn't the right candidate.

The group hammered him in statewide TV ads that portrayed Thompson as a longtime politician who has supported tax and spending increases, as well as the federal health care law critics dub "Obamacare."

Thompson faced similar questions during the press conference earlier this month, after he criticized President Barack Obama for his handling of the federal deficit.

"I balanced the budget every time I was governor, for 14 years," he said. "I took over two-thirds of the cost of education and gave the people of Wisconsin a property tax cut."

But critics say that approach led to a series of structural deficits at the end of Thompson's tenure, the result of balancing budgets with one-time funds. When asked recently if he took responsibility for the structural deficits during his time as governor, Thompson said, "No, I do not. I take responsibility for cutting people's taxes."

Lucrative second career

Thompson left his post as governor in 2001 when he was appointed secretary of the U.S. Department of Health and Human Services by President George W. Bush. He served in that position until 2005.

Since leaving public office, Thompson has done well for himself financially, serving as a consultant and board member for a slew of corporations.

Thompson reported at least $13 million in assets and more than $5 million in income since the beginning of 2010 in Senate disclosure forms. In 2011, he reported more than a dozen sources of earned and non-investment income, including his $771,000 salary from the international law firm Akin Gump Strauss Hauer & Feld, a $254,000 salary from Logistics Health in La Crosse and about $3 million from the sale of the same company, which does health care management for government and commercial organizations, and $50,000 from Kikkoman Corp., the Walworth-based company known for its soy sauce.

And the report included about three dozen positions he's held with various corporations, nonprofits and a law firm.

Both liberal and conservative critics have seized on Thompson's web of financial interests.

"If Tommy Thompson is so busy serving these corporate interests, how can Wisconsin trust the ultimate Washington insider and lobbyist to serve the people in the U.S. Senate?" said Mike Tate, chairman of the Democratic Party of Wisconsin.

But Thompson's campaign has repeatedly pointed out that he has never been a registered lobbyist.

"He has resigned all his day-to-day responsibilities in the private sector in order to focus on his U.S. Senate campaign, and he'll resign his board leadership roles once elected to the Senate," Schmitz said.

Liberal and conservative critics in turn accuse Thompson of simply being a lobbyist by another name. Unlike Neumann, who made his money as a Nashotah homebuilder, and Hovde, who made his millions as a Washington, D.C.-based hedge fund manager, Thompson has been accused of using his prominent government positions and ties to the private sector to make money after leaving public office.

"The money he's made and the interests he's represented will raise some red flags," said Mike McCabe, executive director of the Wisconsin Democracy Campaign, which tracks money in politics. "There's a coziness there that's troubling."

Attacking Tommy

But are these issues enough to hamstring Thompson? It doesn't appear so.

Thompson is leading in most polls, and according to January campaign finance filings, the most recent available, he has raised $656,000. Neumann has raised $518,000, although his campaign said he has since passed the $1 million mark. Fitzgerald raised $77,000. Hovde didn't enter the race until March 8.

Lee said Thompson's opponents have to be careful how vigorously they attack the former governor.

"You won't find many Republicans who don't at least like Tommy," he said. "So they have the tough job of attacking Tommy, without actually attacking Tommy."