2020Final results
2020 election for Iowa Senate District 12
Iowa State Senate · Iowa
Mark Costello (R) won with 69.0% of the vote, defeating Joseph Norris (D) by 38.2 points.
Mark CostelloRepublican · winner · incumbent
69.0%20,165
Joseph NorrisDemocrat
30.8%8,999
29,215 votes
Source: MIT Election Data and Science LabUpdated Oct 1, 2026, 10:09 AM ET
The seat over time
D − R margin in this seat's races around 2020
Races before and after
Source: MIT Election Data and Science LabUpdated Oct 1, 2026, 10:09 AM ET