Former Wisconsin Gov. Tommy Thompson (R) has won his Senate primary, giving Republicans their strongest candidate to win the open seat this fall.

The longtime Wisconsin political fixture faced a tough race, largely because of the rightward shift of the state’s Republican base in recent years and earlier work Thompson had done in pushing centrist healthcare solutions. But a fractured field helped him squeak to victory.

{mosads}With 82 percent of precincts reporting, Thompson led a four-way field with 35 percent of the vote, followed by businessman Eric Hovde (R) at 30 percent, former Rep. Mark Neumann (R-Wis.) at 23 percent and Wisconsin Assembly Speaker Jeff Fitzgerald at 12 percent. The Associated Press has called the race.

Thompson will face Rep. Tammy Baldwin (D-Wis.), who was uncontested in her primary. Polls show the race will be competitive in the slightly Democratic-leaning state: In the last three public surveys of the race, Thompson leads in one, Baldwin leads in another and they are tied in the third. Thompson likely starts the race with a slight edge due to his popularity with independents in the state, though Baldwin has the cash advantage at this point.

Democrats have said they’ll hit Thompson on his years in Washington, D.C., following his time working as President George W. Bush’s secretary of Health and Human Services, which he spent working as a consultant for a number of health insurance groups. Republicans have promised to make Baldwin’s strongly liberal record a top target, especially her support of a single-payer, government-run healthcare system.

Both sides came out firing quickly after the primary was called.

“Gov. Thompson’s election ensures that the people of Wisconsin will have a clear choice this November,” said National Republican Senatorial Committee Chairman John Cornyn (Texas) in a statement. “While Tommy has been a longtime fighter for fixing our nation’s economy and protecting Medicare, Congresswoman Baldwin finds herself to the far left of even President Obama on some of the most important issues facing Americans — a complete government takeover of our healthcare system, record tax hikes on families and businesses and more debt that future generations will never be able to repay.”

The Democratic Senatorial Campaign Committee fired back.

“Tommy Thompson is out for the special interests and not Wisconsin,” said DSCC spokesman Matt Canter in a statement. “After 38 years in politics, Tommy Thompson cashed in and made millions lobbying on behalf of special-interest clients for a lobbying firm in Washington, D.C. Thompson used his D.C. connections to enrich himself and leave taxpayers holding the bill. He helped secure sweetheart deals for his special-interest clients and was paid big bucks from companies that outsourced U.S. jobs.”

It became clear early on that the longtime titan of Wisconsin Republican politics had a fight on his hands despite his near-universal name recognition. Polls showed Thompson with a large but soft lead, and the deep-pocketed, fiscally conservative Club for Growth made it clear he was a top target. Thompson’s fundraising totals were unimpressive for a man with his political connections, and many Republican observers in the state and nationally quietly predicted he wouldn’t hold on in the race.

But Neumann, despite his conservative bona fides, faced resistance from some in the party’s base because of lingering resentment following a testy 2010 primary against now-Gov. Scott Walker (R), and Hovde’s entrance into the race completely scrambled the situation. Hovde spent $4 million of his own money to quickly raise his name identification, and polls showed him closing quickly on the former governor.

Thompson might have also benefited from the surprisingly low profile of
the race. Many Wisconsin voters were exhausted after Walker’s
hard-fought recall election victory, and while Hovde and Neumann both
seemed to have some momentum heading into the final days of the race,
Mitt Romney’s choice of favorite son and Rep. Paul Ryan (R-Wis.) to be
his vice presidential nominee sucked all of the oxygen out of the contest
in its final days.

The shortened primary season, due to the recall’s early summer date,
also meant that Hovde couldn’t further leverage his fundraising edge
against Thompson.

The former governor was endorsed by a number of Republicans he’d known for years: former Arkansas Gov. Mike Huckabee (R), former House Speaker Newt Gingrich (R-Ga.) and Indiana Gov. Mitch Daniels (R). While Ryan, like Walker, didn’t endorse in the race, he gave Thompson a shout-out during a Sunday rally with Romney in the state.

This post was updated at 11:55 p.m.