Former Assembly Speaker Mike Sheridan is one of three Democrats who filed to run for the Senate seat being vacated by retiring Sen. Tim Cullen. The other two are state Rep. Janis Ringhand and Janesville native Austin Scieszinski.
Republican Brian Fitzgerald also filed for that seat.
Two Democrats have also submitted signatures to run in the seat being vacated by retiring Sen. Dale Schultz. They are Pat Bomhack, a former staffer of former U.S. Sen. Russ Feingold, and Ernie Wittwer, a former state Department of Transportation official.
Republican Rep. Howard Marklein is also running for that seat.
Seventeen Senate seats and all 99 Assembly seats are up.