2018Final results
2018 election for Illinois's 12th District
U.S. House · Illinois
Mike Bost (R) won with 51.6% of the vote, defeating Brendan Kelly (D) by 6.2 points.
Mike BostRepublican · winner
51.6%134,884
Brendan KellyDemocrat
45.4%118,724
Randy AuxierGreen
3.0%7,935
261,543 votes
Source: MIT Election Data and Science LabUpdated Oct 1, 2026, 6:17 AM ET
The seat over time
D − R margin in this seat's races around 2018
Races before and after
Source: MIT Election Data and Science LabUpdated Oct 1, 2026, 6:17 AM ET
Money in this race
Each line compares the two campaigns on one scale.
Brendan KellyMike Bost
$3.9M
Raised by the campaign
$2.9M
$3.9M
Spent by the campaign
$2.9M
$4.1K
Cash on hand
$5.3K
Other candidates' campaigns: Randy Auxier $15K.
Campaign money: FEC, through Dec 31, 2018.
Source: FEC campaign filingsUpdated Dec 31, 2018