MADISON, Wis. — The toughest opponent Tommy Thompson may have to overcome in next year's U.S. Senate race is Tommy Thompson himself.
The former Wisconsin governor and U.S. Cabinet secretary was set to formally launch his Senate bid with a rally Thursday, 13 years since he last appeared on a ballot.
Early in the campaign, Thompson has found himself under criticism from Democrats and Republicans alike over his shifting position on President Barack Obama's health care reform law. And conservatives in his party say his record as governor and as President George W. Bush's first health and human services secretary was far too moderate.
"The world has changed since he was elected to office," said Chris Chocola, the president of the conservative Club for Growth, which has endorsed one of his opponents, former U.S. Rep. Mark Neumann. "Now we're talking about how much less we'll spend rather than how much more we'll spend."
The growth in state spending and the size of government during his 14 years as governor are being cast as a liability by Thompson's rivals, and his consensus-building approach to politics seems almost quaint in the current bitterly partisan political environment.
But Thompson has some things the two more conservative GOP candidates in the race don't: More than 40 years in public life, unparalleled name recognition, and a vast reservoir of good will.
"It's going to be a very bloody, divisive primary where most of the fire is focused on Thompson and his big spending record and flip flopping on issues," said Matt Canter, a spokesman for the Democratic Senatorial Campaign Committee.
The seat, which has been in Democratic hands since 1957, is opening due to Herb Kohl's retirement. A victory in Wisconsin would be a major pickup for Republicans looking to regain control of the Senate.
One of those challenging Thompson is Jeff Fitzgerald, the conservative speaker of the Wisconsin state Assembly, who helped shepherd through the Legislature Gov. Scott Walker's proposal attacking union rights. The other is Neumann, who has the support of both the Club for Growth and U.S. Sen. Jim DeMint, a South Carolina Republican who is a favorite among tea party conservatives.
The only Democrat running is U.S. Rep. Tammy Baldwin, a liberal from Madison.
Fitzgerald said his recent record delivering on the conservative agenda sets him apart from Thompson and Neumann.
"I'm kind of the outside guy, the dark horse," Fitzgerald said. "I have the clear cut message that I just delivered on these promises."
Fitzgerald said Thompson's former statements in support of health care reform are a liability.
"I think he's got a problem with that with our base," Fitzgerald said.
Neumann said repealing Obama's health care reform package is one of the top issues with conservative voters and his call for repealing it has been the most consistent message from Republican candidates.
Thompson declined to be interviewed but instead sent an email statement defending his conservative credentials, citing welfare reform and implementation of school choice programs.
"People said I was too conservative to run for governor," Thompson said in the email. "I won and we sparked a successful conservative revolution right here in Wisconsin."
The biggest issue Thompson's had to deal with in the nascent campaign, and one that could be pivotal as he tries to survive a Republican primary, is his position on Obama's health care reform law.
Thompson initially spoke favorably of the law and the need for health care reform, while also raising concerns about some parts of Obama's proposal, including the mandate forcing people to buy health insurance.
As it was working its way through Congress, Thompson called Obama's proposal "another important step" toward achieving health care reform. But he also raised concerns about certain parts of the plan, including the mandate forcing people to buy health insurance.
He now favors repeal of the law, saying it wasn't the right solution.
Thompson reiterated in his email that he was committed to repealing the Obama health care reforms.
Thompson was the strongest Republican advocate for the law at the time it was being debated, said Canter with the Democratic Senatorial Campaign Committee. Obama himself even mentioned Thompson in 2009 as a supporter of health care reform, even though most congressional Republicans oppose it.
By now arguing for repeal, Thompson is "catering to what's in his best political interests," Canter said.
Thompson is facing a problem common to candidates who run for election after long absences from office, said Jack Pitney, a political science professor at Claremont McKenna College. Often the issues of the day and the focus of a party's agenda shift if there's a long gap between runs, he said.
"In the 1990s this country was in a time of great prosperity, and at least the federal budget was in surplus," he said. "It's a completely different situation now."
Thompson, who was first elected to the state Assembly in 1966 and was elected governor four times starting in 1986, has cultivated a base of supporters that is unlikely to leave him, while Fitzgerald and Neumann are fighting over largely the same pool of more conservative voters, said University of Wisconsin political science professor Charles Franklin.
"That divides the more conservative wing of the party which is probably to Thompson's benefit in a three-way race," Franklin said. "Anything he does to divide the competition is probably good."
Henry C. Jackson in Washington contributed to this report.