FILE - In this Aug. 10, 2012, file photo Republican candidates former Wisconsin Gov. Tommy Thompson, center, talk to members of the television audience after a candidates' debate in Mad

 

              FILE - In this Aug. 10, 2012, file photo Republican candidates former Wisconsin Gov. Tommy Thompson, center, talk to members of the television audience after a candidates
FILE - In this Aug. 10, 2012, file photo Republican candidates former Wisconsin Gov. Tommy Thompson, center, talk to members of the television audience after a candidates' debate in Madison, Wis. Even with the name of Thompson, the biggest name in modern Wisconsin politics, on the ballot, the Republican primary in a highly competitive U.S. Senate race appears headed for a fractious four-way battle. (AP Photo/Andy Manis, File)