2016Final results
2016 election for Iowa Senate District 12
Iowa State Senate · Iowa
Mark Costello (R) won with 78.2% of the vote, defeating Don W. Brantz (Lib) by 56.6 points.
Mark CostelloRepublican · winner
78.2%20,012
Don W. BrantzLibertarian
21.6%5,524
25,582 votes
Source: MIT Election Data and Science LabUpdated Oct 1, 2026, 4:52 AM ET
The seat over time
D − R margin in this seat's races around 2016
Races before and after
Source: MIT Election Data and Science LabUpdated Oct 1, 2026, 4:52 AM ET