Brunner and Hovde have gained the support of tea party groups because of their focus on cutting government spending, but they should not be confused with the tea party firebrands such as Sharron Angle and Christine O'Donnell, who won GOP primaries two years ago but hurt their party's ability to win general elections in Nevada and Delaware, respectively. They hit many of the same talking points that rallied GOP voters two years ago, but with a Chamber of Commerce touch that is more likely to win over moderates and independents.
The sizable investments the self-funding candidates are making raise the question of whether they've tilted the playing field with their wealth and whether they're essentially trying to buy an election. Hovde bristles at the question.
"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. And I'm being criticized for making a big investment that's a giant negative return for me?" Hovde said.
All of the big self-funders in this year's Senate races are participating in competitive GOP primaries while the top Democratic candidates in those states are generally running uncontested and can save their resources for the fall.
That dynamic is generally improving the prospects for those Democratic candidates by exposing some major vulnerabilities, said Matt Canter, spokesman for the Democratic Senatorial Campaign Committee.
"It's resulting in some very vicious primaries developing around the country," Canter said.
Brian Walsh, spokesman for the Republican Senatorial Campaign Committee, said hard-fought primaries aren't a problem.
Associated Press writer Scott Bauer in Madison, Wis., contributed to this report.
Copyright 2012 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.