Kleefisch will share the stage with a long list of prominent Wisconsin conservatives including former Gov. Tommy Thompson, Assembly Speaker Jeff Fitzgerald and former U.S. Congressman Mark Neumann, all of whom are running for the U.S. Senate.
The pro-Walker rally was conceived as a small gathering by grass-roots organizers on Facebook and then exploded into a major event as one after another GOP leader got on board.
Kleefisch, the latest to sign on, is also being subjected to a recall election along with Gov. Scott Walker and four Republican state sentators.
"We are thrilled to have Rebecca join us," said Paris Procopis, one of the event organizers. "This gives us the opportunity to thank her and show that we are all still solidly behind her and Scott."
"The very fact that she is coming to our grass roots event shows us that not only do we stand with Rebecca, it shows that she also stands with us."
The event is from 1 to 4 p.m. Saturday at the Rotary Performance Pavilion in Hart Park at North 70th and West Chestnut streets.