A special election for the state Assembly seat previously held by Republican Mark Honadel will be held Nov. 19.
Gov. Scott Walker announced the date of the election on Tuesday.
The 21st Assembly District covers the South Milwaukee and Oak Creek areas.
Honadel left his seat for a job in the private sector. He was elected to the Assembly in 2003 and was one of the lead sponsors of a bill that relaxed Wisconsin's mining standards to jump-start Gogebic Taconite's plans for a giant iron mine near Lake Superior.
Potential candidates can begin circulating nomination papers on Tuesday. They are due on Sept. 24.
If more than one candidate files for the seat, there will be a primary on Oct. 22.