MADISON, Wis. (AP) -- Six candidates have filed paperwork to challenge three Democratic state senators in recall elections this summer.

The nomination papers filed Tuesday show that each race features the Democratic incumbent along with two challengers each registered as a Republican. That means each race would have a Republican primary on July 19 and a general election on Aug. 16.

The paperwork still has to be verified by the state Government Accountability Board. That should wrap up by next week.

The Democrats being targeted for recall are Sens. Dave Hansen of Green Bay, Jim Holperin of Conover and Robert Wirch of Pleasant Prairie. They're being targeted for opposing Republican Gov. Scott Walker's efforts to remove collective-bargaining rights from most public workers.

Six Republican state senators are also being targeted for supporting that measure.