Hovde is making the most noise, spending at least $4 million of his own money on a steady stream of ads that make the case for his fiscal conservatism and attack Thompson and Neumann.
The outsider businessman approach was successful for other Republican candidates in 2010 such as Johnson, Michigan Gov. Rick Snyder and Florida Gov. Rick Scott. Hovde said he models his campaign on that of Johnson, who also came out of nowhere and managed to knock off Democratic Sen. Russ Feingold.
Hovde worked as a hedge fund investor for 24 years in Washington, experience that his opponents attack. They also point to a spotty voting record and business deals with the government that appear to run contrary to his anti-spending rhetoric.
"I'm taking my hard-earned money because I care about my country passionately and I'm worried it's going to go through a financial collapse," Hovde said. "And I'm being criticized for making a big investment that's a giant negative return for me?"
Neumann, who spent four years in Congress in the 1990s, has the most support from tea party groups including the Tea Party Express, the conservative Club for Growth, and U.S. Sens. Jim DeMint, R-S.C., and Rand Paul, R-Ky.
Polls suggest Neumann has surged in recent weeks, putting him in position to pull a surprise in Wisconsin similar to the one engineered in Texas by Ted Cruz. A tea party candidate, Cruz shocked the Texas Republican establishment with his win last month in the GOP Senate primary.
Fitzgerald, a close ally of Walker's who helped push his conservative agenda through the Legislature, lagged in fundraising and in the polls.
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