Three candidates have signed the the Taxpayer Protection Pledge in their bid for the seat being vacated by retiring Sen. Herb Kohl: Former Wisconsin Gov. Tommy Thompson, State Sen. Frank Lasee, and former Congressman Mark Neumann.  

Other announced candidates for the Republican nomination include State Assembly Speaker Jeff Fitzgerald, and retired delivery driver John Schiess. Congresswoman Tammy Baldwin and social services worker Gregory Paules are the only candidates vying for the Democrat nomination at this point.

Last year Republicans scored big wins in Wisconsin. Republican Sen. Ron Johnson defeated four term incumbent Democrat Sen. Russ Feingold by a margin of 52% to 47%. Gov. Scott Walker also similarly defeated Democrat Tom Barrett by a margin of 52% to 46%. Republicans didn't only win state-wide elections; they also reversed control of both houses of the state legislature. The success of Republicans in Wisconsin in 2010 is why 2012's Wisconsin Senate race is rated as a toss up by Larry Sabato's Crystal Ball and the Cook Political Report.

By signing the Pledge, Thompson, Lasee, and Neumann commit to the taxpayers of Wisconsin that they will “oppose any and all efforts to increase the marginal income tax rates for individuals and/or businesses … and oppose any net reduction or elimination of deductions and credits, unless matched dollar for dollar by further reducing tax rates.”