Illinois' 12th Congressional District

Illinois' 12th Congressional District

Incumbent

Mike Bost

Assumed office: January 3, 2015

Illinois' 12th Congressional District in the United States House of Representatives is represented by Mike Bost (R).

As of the 2020 Census, Illinois representatives represented an average of 754,279 residents. After the 2010 Census, each member represented 714,688 residents.

Elections

• 2030
• 2028
• 2026
• 2024
• 2022
• 2020
• 2018

See also: Illinois's 12th Congressional District election, 2030

There are no official candidates yet for this election.

See also: Illinois' 12th Congressional District election, 2028

There are no official candidates yet for this election.

See also: Illinois' 12th Congressional District election, 2026

General election

The primary will occur on March 17, 2026. The general election will occur on November 3, 2026. General election candidates will be added here following the primary.

Democratic primary

Democratic primary for U.S. House Illinois District 12

Julie Fortier (D) is running in the Democratic primary for U.S. House Illinois District 12 on March 17, 2026.

		Candidate
	Submit photo	Julie Fortier

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	There are no incumbents in this race.
= candidate completed the Ballotpedia Candidate Connection survey.
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Republican primary

Republican primary for U.S. House Illinois District 12

Incumbent Mike Bost (R) is running in the Republican primary for U.S. House Illinois District 12 on March 17, 2026.

		Candidate
		Mike Bost

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	Incumbents are bolded and underlined.
= candidate completed the Ballotpedia Candidate Connection survey.
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Withdrawn or disqualified candidates

• Michael Tabacchi (R)

See also: Illinois' 12th Congressional District election, 2024

General election

General election for U.S. House Illinois District 12

Incumbent Mike Bost (R) defeated Brian Roberts (D) in the general election for U.S. House Illinois District 12 on November 5, 2024.

		Candidate	%	Votes
✔		Mike Bost (R)	74.2	272,754
		Brian Roberts (D)	25.8	94,875

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	Incumbents are bolded and underlined. The results have been certified. Source	Total votes: 367,629
= candidate completed the Ballotpedia Candidate Connection survey.
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Democratic primary

Democratic primary for U.S. House Illinois District 12

Brian Roberts (D) defeated Preston Nelson (D) in the Democratic primary for U.S. House Illinois District 12 on March 19, 2024.

		Candidate	%	Votes
✔		Brian Roberts	60.1	10,775
		Preston Nelson	39.9	7,151

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	There were no incumbents in this race. The results have been certified. Source	Total votes: 17,926
= candidate completed the Ballotpedia Candidate Connection survey.
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Withdrawn or disqualified candidates

• Joshua Qualls (D)

Republican primary

Republican primary for U.S. House Illinois District 12

Incumbent Mike Bost (R) defeated Darren Bailey (R) in the Republican primary for U.S. House Illinois District 12 on March 19, 2024.

		Candidate	%	Votes
✔		Mike Bost	51.4	48,770
		Darren Bailey	48.6	46,035

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	Incumbents are bolded and underlined. The results have been certified. Source	Total votes: 94,805
= candidate completed the Ballotpedia Candidate Connection survey.
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See also: Illinois' 12th Congressional District election, 2022

General election

General election for U.S. House Illinois District 12

Incumbent Mike Bost (R) defeated Homer Markel (D) in the general election for U.S. House Illinois District 12 on November 8, 2022.

		Candidate	%	Votes
✔		Mike Bost (R)	75.0	218,379
		Homer Markel (D)	25.0	72,791
		Other/Write-in votes	0.0%	1

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	Incumbents are bolded and underlined. The results have been certified. Source	Total votes: 291,171
= candidate completed the Ballotpedia Candidate Connection survey.
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Democratic primary

Democratic primary for U.S. House Illinois District 12

Homer Markel (D) defeated Joshua Qualls (D) in the Democratic primary for U.S. House Illinois District 12 on June 28, 2022.

		Candidate	%	Votes
✔		Homer Markel	56.7	11,068
		Joshua Qualls	43.3	8,438

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	There were no incumbents in this race. The results have been certified. Source	Total votes: 19,506
= candidate completed the Ballotpedia Candidate Connection survey.
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Withdrawn or disqualified candidates

• Keith Richardson (D)

Republican primary

Republican primary for U.S. House Illinois District 12

Incumbent Mike Bost (R) advanced from the Republican primary for U.S. House Illinois District 12 on June 28, 2022.

		Candidate	%	Votes
✔		Mike Bost	100.0	88,681

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	Incumbents are bolded and underlined. The results have been certified. Source	Total votes: 88,681
= candidate completed the Ballotpedia Candidate Connection survey.
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See also: Illinois' 12th Congressional District election, 2020

General election

General election for U.S. House Illinois District 12

Incumbent Mike Bost (R) defeated Ray Lenzi (D) in the general election for U.S. House Illinois District 12 on November 3, 2020.

		Candidate	%	Votes
✔		Mike Bost (R)	60.4	194,839
		Ray Lenzi (D)	39.6	127,577

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	Incumbents are bolded and underlined. The results have been certified. Source	Total votes: 322,416
= candidate completed the Ballotpedia Candidate Connection survey.
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Withdrawn or disqualified candidates

• Brian Boeving (Federalist Party)

Democratic primary

Democratic primary for U.S. House Illinois District 12

Ray Lenzi (D) defeated Joel Funk (D) in the Democratic primary for U.S. House Illinois District 12 on March 17, 2020.

		Candidate	%	Votes
✔		Ray Lenzi	50.3	27,015
		Joel Funk	49.7	26,648

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	There were no incumbents in this race. The results have been certified. Source	Total votes: 53,663
= candidate completed the Ballotpedia Candidate Connection survey.
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Republican primary

Republican primary for U.S. House Illinois District 12

Incumbent Mike Bost (R) advanced from the Republican primary for U.S. House Illinois District 12 on March 17, 2020.

		Candidate	%	Votes
✔		Mike Bost	100.0	40,222

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	Incumbents are bolded and underlined. The results have been certified. Source	Total votes: 40,222
= candidate completed the Ballotpedia Candidate Connection survey.
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See also: Illinois' 12th Congressional District election, 2018

General election

General election for U.S. House Illinois District 12

Incumbent Mike Bost (R) defeated Brendan Kelly (D) and Randy Auxier (G) in the general election for U.S. House Illinois District 12 on November 6, 2018.

		Candidate	%	Votes
✔		Mike Bost (R)	51.6	134,884
		Brendan Kelly (D)	45.4	118,724
		Randy Auxier (G)	3.0	7,935

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	Incumbents are bolded and underlined. The results have been certified. Source	Total votes: 261,543 (100% precincts reporting)
= candidate completed the Ballotpedia Candidate Connection survey.
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Democratic primary

Democratic primary for U.S. House Illinois District 12

Brendan Kelly (D) defeated David Bequette (D) in the Democratic primary for U.S. House Illinois District 12 on March 20, 2018.

		Candidate	%	Votes
✔		Brendan Kelly	81.0	40,555
		David Bequette	19.0	9,526

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	There were no incumbents in this race. The results have been certified.	Total votes: 50,081
= candidate completed the Ballotpedia Candidate Connection survey.
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Withdrawn or disqualified candidates

• Charles Koen (D)

Republican primary

Republican primary for U.S. House Illinois District 12

Incumbent Mike Bost (R) defeated Preston Nelson (R) in the Republican primary for U.S. House Illinois District 12 on March 20, 2018.

		Candidate	%	Votes
✔		Mike Bost	83.5	31,658
		Preston Nelson	16.5	6,258

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	Incumbents are bolded and underlined. The results have been certified.	Total votes: 37,916
= candidate completed the Ballotpedia Candidate Connection survey.
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Green Party primary

Green primary for U.S. House Illinois District 12

Randy Auxier (G) advanced from the Green Party primary for U.S. House Illinois District 12 on March 20, 2018.

		Candidate	%	Votes
✔		Randy Auxier	100.0	131

---

	There were no incumbents in this race. The results have been certified.	Total votes: 131
= candidate completed the Ballotpedia Candidate Connection survey.
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Previous election results

2016

See also: Illinois' 12th Congressional District election, 2016

Heading into the election, Ballotpedia rated this race as safely Republican. Incumbent Mike Bost (R) defeated C.J. Baricevic (D) and Paula Bradshaw (G) in the general election on November 8, 2016. Bost and Baricevic both ran unopposed in their respective primaries, while Paula Bradshaw defeated Sadona Folkner to win the Green Party nomination.

U.S. House, Illinois District 12 General Election, 2016

Party		Candidate	Vote %	Votes
	Republican	Mike Bost Incumbent	54.3%	169,976
	Democratic	C.J. Baricevic	39.7%	124,246
	Green	Paula Bradshaw	6%	18,780
Total Votes				313,002
Source: Illinois State Board of Elections

U.S. House, Illinois District 12 Green Party Primary, 2016

Candidate	Vote %	Votes
Paula Bradshaw	80.1%	117
Sadona Folkner	19.9%	29
Total Votes		146
Source: Illinois State Board of Elections

2014

See also: Illinois' 12th Congressional District elections, 2014

Illinois' 12th Congressional District was a battleground district in 2014 due to the fact that the district had nearly even numbers of registered Democratic and Republican voters. Both incumbent William Enyart (D) and Mike Bost (R) advanced through their primaries with no challenge. They faced off in the general election on November 4, 2014, along with Green Party candidate Paula Bradshaw. Challenger Mike Bost (R) defeated incumbent William Enyart (D) and fellow challenger Paula Bradshaw (G) in the general election.

U.S. House, Illinois District 12 General Election, 2014

Party		Candidate	Vote %	Votes
	Republican	Mike Bost	52.5%	110,038
	Democratic	Bill Enyart Incumbent	41.9%	87,860
	Green	Paula Bradshaw	5.6%	11,840
Total Votes				209,738
Source: Illinois State Board of Elections Official Results

General election candidates

• Mike Bost
• William Enyart - Incumbent
• Paula Bradshaw

March 18, 2014, primary results

Republican Primary

• Mike Bost: State Representativea

Democratic Primary

• William Enyart - Incumbenta

Green Party Primary

• Paula Bradshawa

2012

See also: Illinois' 12th Congressional District elections, 2012

The 12th Congressional District of Illinois held an election for the U.S. House of Representatives on November 6, 2012. William Enyart won the election in the district.

U.S. House, Illinois District 12 General Election, 2012

Party		Candidate	Vote %	Votes
	Democratic	William Enyart	51.7%	157,000
	Republican	Jason Plummer	42.7%	129,902
	Green	Paula Bradshaw	5.6%	17,045
Total Votes				303,947
Source: Illinois Board of Elections "2012 General Election Official Vote Totals"

2010
On November 2, 2010, Jerry F. Costello won re-election to the United States House. He defeated Teri Newman (R) and Rodger Jennings (G) in the general election.

U.S. House, Illinois District 12 General Election, 2010
Party		Candidate	Vote %	Votes
	Democratic	Jerry F. Costello incumbent	59.8%	121,272
	Republican	Teri Newman	36.5%	74,046
	Green	Rodger Jennings	3.6%	7,387
Total Votes				202,705

2008
On November 4, 2008, Jerry F. Costello won re-election to the United States House. He defeated Timmy Jay Richardson, Jr. (R), Rodger W. Jennings (G) and Harold Wiegand (Write-in) in the general election.

U.S. House, Illinois District 12 General Election, 2008
Party		Candidate	Vote %	Votes
	Democratic	Jerry F. Costello incumbent	71.4%	212,891
	Republican	Timmy Jay Richardson, Jr.	24.9%	74,382
	Green	Rodger Jennings	3.7%	10,907
	Write-in	Harold Wiegand	0%	1
Total Votes				298,181

2006
On November 7, 2006, Jerry F. Costello won re-election to the United States House. He ran unopposed in the general election.

U.S. House, Illinois District 12 General Election, 2006
Party		Candidate	Vote %	Votes
	Democratic	Jerry F. Costello incumbent	100%	157,284
	Write-in	Write-in	0%	7
Total Votes				157,291

2004
On November 2, 2004, Jerry F. Costello won re-election to the United States House. He defeated Erin R. Zweigart (R), Walter B. Steele (L) in the general election.

U.S. House, Illinois District 12 General Election, 2004
Party		Candidate	Vote %	Votes
	Democratic	Jerry F. Costello incumbent	69.5%	198,962
	Republican	Erin R. Zweigart	28.9%	82,677
	Libertarian	Walter B. Steele	1.7%	4,794
	Write-in	Write-in	0%	2
Total Votes				286,435

2002
On November 5, 2002, Jerry F. Costello won re-election to the United States House. He defeated David Sadler (R) in the general election.

U.S. House, Illinois District 12 General Election, 2002
Party		Candidate	Vote %	Votes
	Democratic	Jerry F. Costello incumbent	69.2%	131,580
	Republican	David Sadler	30.8%	58,440
Total Votes				190,020

2000
On November 7, 2000, Jerry F. Costello won re-election to the United States House. He ran unopposed in the general election.

U.S. House, Illinois District 12 General Election, 2000
Party		Candidate	Vote %	Votes
	Democratic	Jerry F. Costello incumbent	100%	183,208
	Write-in	Write-in	0%	49
Total Votes				183,257

District map

Redistricting

2020-2021

See also: Redistricting in Illinois after the 2020 census

Illinois enacted a congressional map on November 24, 2021, after Gov. J.B. Pritzker (D) signed the proposal into law. The Illinois State Senate voted 41-18 in favor of the map on October 28, 2021, followed by the Illinois House of Representatives voting 71-43 in favor on October 29, 2021.

How does redistricting in Illinois work? The Illinois General Assembly is responsible for drawing both congressional and state legislative district lines. Both chambers of the state legislature must approve a redistricting plan. The governor may veto the lines drawn by the state legislature.

In the event that both chambers of the state legislature do not approve a legislative redistricting plan, a backup commission must draw the lines. The majority and minority leaders of each chamber must appoint two members each to the commission (one legislator and one general citizen). Of the eight commission members, no more than four may belong to the same political party. In the event that these eight members cannot approve a plan, the Illinois Supreme Court must select two individuals (from different political parties) as potential tiebreakers. The secretary of state must then appoint one of these individuals to the backup commission to break the tie.

The Illinois Constitution requires that state legislative districts be "contiguous and reasonably compact." There are no such requirements in place for the state's congressional districts.

State law also mandates the establishment of state legislative districts "that allow racial or language minority communities to elect--or influence the election of--the candidates of their choice, even if no comparable district would be required by the federal Voting Rights Act."

2020

2024

2010-2011

This is the 12th Congressional District of Illinois after the 2001 redistricting process.

See also: Redistricting in Illinois after the 2010 census

In 2011, the Illinois State Legislature re-drew the congressional districts based on updated population information from the 2010 census.

District analysis

See also: The Cook Political Report's Partisan Voter Index

See also: FiveThirtyEight's elasticity scores

2026

Heading into the 2026 elections, based on results from the 2024 and 2020 presidential elections, the Cook Partisan Voter Index for this district is R+22. This meant that in those two presidential elections, this district's results were 22 percentage points more Republican than the national average. This made Illinois' 12th the 23rd most Republican district nationally.

2024

Heading into the 2024 elections, based on results from the 2020 and 2016 presidential elections, the Cook Partisan Voter Index for this district was R+24. This meant that in those two presidential elections, this district's results were 24 percentage points more Republican than the national average. This made Illinois' 12th the 18th most Republican district nationally.

Daily Kos calculated what the results of the 2020 presidential election in this district would have been following redistricting. Donald Trump (R) would have defeated Joe Biden (D) 70.5%-27.7%.

2022

Heading into the 2022 elections, based on results from the 2020 and 2016 presidential elections, the Cook Partisan Voter Index for this district was R+24. This meant that in those two presidential elections, this district's results were 24 percentage points more Republican than the national average. This made Illinois' 12th the 15th most Republican district nationally.

Daily Kos calculated what the results of the 2020 presidential election in this district would have been following redistricting. Joe Biden (D) would have received 27.7% of the vote in this district and Donald Trump (R) would have received 70.5%.

2018

Heading into the 2018 elections, based on results from the 2016 and 2012 presidential elections, the Cook Partisan Voter Index for this district was R+5. This meant that in those two presidential elections, this district's results were 5 percentage points more Republican than the national average. This made Illinois' 12th Congressional District the 192nd most Republican nationally.

FiveThirtyEight's September 2018 elasticity score for states and congressional districts measured "how sensitive it is to changes in the national political environment." This district's elasticity score was 1.17. This means that for every 1 point the national political mood moved toward a party, the district was expected to move 1.17 points toward that party.

See also

• Redistricting in Illinois
• Illinois' 12th Congressional District election, 2024
• Illinois' 12th Congressional District election, 2022
• Illinois' 12th Congressional District election, 2020
• Illinois' 12th Congressional District election, 2018

External links

• GovTrack District 12

Footnotes

[show]

Illinois' current delegation to the United States Congress

Senators

Tammy Duckworth (D)

Dick Durbin (D)

Representatives

District 1

Jonathan Jackson (D)

District 2

Robin Kelly (D)

District 3

Delia Ramirez (D)

District 4

Jesus Garcia (D)

District 5

Mike Quigley (D)

District 6

Sean Casten (D)

District 7

Danny Davis (D)

District 8

Raja Krishnamoorthi (D)

District 9

Jan Schakowsky (D)

District 10

Brad Schneider (D)

District 11

Bill Foster (D)

District 12

Mike Bost (R)

District 13

Nikki Budzinski (D)

District 14

Lauren Underwood (D)

District 15

Mary Miller (R)

District 16

Darin LaHood (R)

District 17

Eric Sorensen (D)

Democratic Party (16)

Republican Party (3)