Former state Rep. Roger Roth said he is running for the state Senate seat now held by retiring Senate President Mike Ellis.
Ellis announced earlier this month he would not seek re-election after more than four decades in state politics.
Roth is an Appleton Republican who served two terms in the Assembly before leaving in 2011. He released a statement late Monday announcing his decision to run.
Roth is the only Republican candidate who has expressed interest thus far in the seat in the Republican-leaning district.
Democratic Rep. Penny Bernard Schaber also is running for the seat.