How does Chicago dominate Illinois elections?

Cook County (Chicago and inner suburbs) contains roughly 40% of Illinois's total population and votes Democratic by 60-70 point margins. Chicago proper gives Democrats 80%+. The Cook County Democratic machine — one of the last big-city political machines still functioning — generates enormous turnout advantages. Democrats can build a 1-million-vote margin in Cook County alone before a single downstate vote is cast. This structural advantage makes Illinois safe Democratic at the statewide level even though the vast majority of Illinois's geographic area votes Republican, often by 30+ points.

Who is Raja Krishnamoorthi and why is he the frontrunner for Illinois Senate?

Raja Krishnamoorthi is an Indian-American Democratic congressman from IL-8 (northwest Chicago suburbs, DuPage and Cook counties) who has represented the district since 2017. He announced his candidacy for Dick Durbin's Senate seat in 2026, citing Durbin's retirement announcement. Krishnamoorthi is well-funded, has a strong suburban Chicago base, and represents the kind of diverse, college-educated suburban coalition that has driven Illinois Democratic politics since 2016. He faces a competitive primary but starts with significant name recognition and fundraising advantages.

What is Illinois's 2026 Senate race outlook?

Dick Durbin announced he will retire rather than seek a fifth Senate term in 2026, ending a 28-year Senate career. Illinois is safe Democratic at D+17 in presidential elections, meaning the Democratic primary winner is the overwhelming favorite in the general. Krishnamoorthi, IL-7's Danny Davis, and other candidates have explored the race. The Republican general-election candidate faces essentially the same structural challenge Republicans always face in Illinois — winning Chicago-area votes at a level that is structurally impossible given the Cook County machine and collar-county Democratic shift.

Safe Democratic — Chicago Machine State

Illinois Polling History
1988–2024

D+17 at the presidential level, entirely driven by Chicago’s Cook County machine. Rural Illinois runs R+30. Durbin’s 2026 retirement creates the first open Senate majority math in a generation — a Krishnamoorthi primary likely decides who holds it for decades.

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Presidential Results 1988–2024

Year	D%	R%	Winner	Margin
1988	48.6%	50.7%	Bush (R)	R +2.1
1992	48.6%	34.3%	Clinton (D)	D +14.3
1996	54.3%	36.8%	Clinton (D)	D +17.5
2000	54.6%	42.6%	Gore (D)	D +12.0
2004	54.8%	44.5%	Kerry (D)	D +10.3
2008	61.9%	36.8%	Obama (D)	D +25.1
2012	57.6%	40.7%	Obama (D)	D +16.9
2016	55.8%	38.8%	Clinton (D)	D +17.1
2020	57.5%	40.5%	Biden (D)	D +17.2
2024	55.4%	41.0%	Harris (D)	D +13.5

Analysis

The State’s Political Story

Illinois was narrowly Republican as recently as 1988 (Bush +2). Clinton flipped it in 1992 and it has been safely Democratic ever since. Obama’s 2004 Senate blowout (+43) against Alan Keyes nationalized Chicago as a Democratic symbol. His 2008 presidential win (D+25) was his largest margin outside DC. The 2024 result (D+13.5) was a modest tightening as Trump improved with Black and Hispanic voters in Chicago, but the Cook County structural advantage remains overwhelming and the collar-county shift is durable.

Key Demographic Drivers

Cook County (Chicago + inner suburbs) provides 1-1.5 million Democratic net votes at D+45-55. The five collar counties (DuPage, Will, Lake, Kane, McHenry) have shifted from reliably Republican to split since 2016. DuPage — once labeled America’s most Republican suburban voters — went narrowly Democratic in 2020. Downstate Springfield, Peoria, and Rockford are R+20-30. Rural southern Illinois mimics Kentucky/Tennessee at R+35-50. The structural Democratic advantage is geography, not demography — Chicago’s population density simply overwhelms the rural land mass.

2026 Context

Dick Durbin’s retirement after 28 Senate years creates Illinois’s most consequential Democratic primary in a generation. Raja Krishnamoorthi (IL-8) is the frontrunner with strong suburban Chicago support and fundraising. The general election will be a walkover for any Democrat given the D+14-17 baseline — Illinois Republicans have not won a Senate race since Peter Fitzgerald in 1998. The competitive story is entirely within the Democratic primary and which candidate inherits Durbin’s coalition of Chicago machine loyalty, suburban college-educated voters, and downstate labor.