Posted Monday, July 30, 2102 --- 6:20 a.m.

MADISON, Wis. (AP) -- The four Republican U.S. Senate candidates plan to debate on a radio show Monday.

It is the first of two scheduled debate featuring all four of the candidates leading up to the Aug. 14 primary. They also plan to debate on Aug. 10.

The candidates are former Gov. Tommy Thompson, hedge fund manager Eric Hovde, former U.S. Rep. Mark Neumann and state Assembly Speaker Jeff Fitzgerald.

The winner will advance to meet Democratic U.S. Rep. Tammy Baldwin in the Nov. 6 general election.

Wisconsin's Senate seat is open due to the retirement of Democrat Herb Kohl.

Monday's debate is being moderated by Green Bay conservative talk radio personality Jerry Bader with questions coming from three broadcast journalists.

Copyright 2012. The Associated Press.