Illinois Primary 2018: A Complete Guide to the Candidates and Results

Overview of the 2018 Illinois Primary

The 2018 Illinois primary, held on March 20, was a pivotal nominating election that determined each party’s candidates for the U.S. House, U.S. Senate, governor, lieutenant governor, attorney general, secretary of state, comptroller, and treasurer. As a heavily Democratic state, the primary largely set the general election lineup, making candidate selection and voter turnout decisive for the November ballot. This guide explains the structure of the ballot, verifies candidate slates, and provides durable context useful for understanding primary dynamics in Illinois.

Ballot Structure and Key Races

Illinois uses a partisan primary with candidates listed by office and party. Registered voters may vote in any one party’s primary but not both. Offices on the 2018 ballot included President (via preference vote), U.S. Senate, U.S. House districts, governor and lieutenant governor (running as a ticket), attorney general, secretary of state, comptroller, and treasurer. Turnout was influenced by competitive gubernatorial and Senate contests, with suburban Cook County and downstate counties showing distinct voting patterns that shaped which nominees advanced to November.

U.S. Senate Candidates

Two major party primaries stood out for their significance: the U.S. Senate Democratic primary and the Republican primary. On the Democratic side, first-term U.S. Representative Tammy Duckworth defeated former securities regulator and nonprofit leader Andrea Slesinger and others, reinforcing a party consensus around an Iraq War veteran with executive branch experience. In the Republican primary, State Representative Jim Durkin prevailed over perennial candidate Bill Brady, who had sought the nomination in multiple cycles. Duckworth’s primary win set up a general election contest against incumbent Republican Senator Mark Kirk, which she won decisively.

Notable Senate Primary Details

• Tammy Duckworth (D): Iraq War veteran, U.S. Representative from the 8th district.
• Andrea Slesinger (D): Public policy professional and former federal official.
• Jim Durkin (R): Minority Leader in the Illinois House at the time.
• Bill Brady (R): Longtime candidate with prior bids for governor and Senate.

Gubernatorial and Lieutenant Governor Races

The Democratic gubernatorial primary featured incumbent Lieutenant Governor Juliana Stratton, who faced challenges from state Representative Lisa Hernandez and former Chicago Public Schools official Maria Hernandez. Stratton won the nomination and ran with J.B. Pritzker, a wealthy businessman and philanthropist who defeated state Senator Daniel Biss and others for the nomination. On the Republican side, incumbent Governor Bruce Rauner faced internal party pressure and a primary challenge, reflecting broader tensions within the state party. The lieutenant governor nominee ran alongside each party’s gubernatorial choice, shaping the executive branch lineup on the November ballot.

Gubernatorial and Lieutenant Governor Slates

Other Key Partisan Races

Down-ballot contests drew attention from party committees and interest groups, particularly where incumbents faced challengers or the races had implications for legislative majorities. In the U.S. House, most incumbents ran unchallenged in their primaries, but a few competitive districts saw contested nominating contests. Statewide officers, including attorney general, comptroller, treasurer, and secretary of state, featured primaries that largely followed party endorsements, with incumbents generally securing renomination. These races solidified the Democratic slate for the general election, a reflection of Illinois’s partisan distribution and primary competitiveness.

General Election Context

By late March 2018, the primary had effectively determined the November lineup. Democratic nominees for statewide office—such as J.B. Pritzker for governor, Kwame Raoul for attorney general, and Susana Mendoza for comptroller—entered the general with fundraising and organizational advantages. Republican nominees, including Bruce Rauner and his lieutenant gubernatorial candidate, faced the challenge of uniting a party base after primary contests. The March primary results were thus consequential, influencing campaign dynamics, fundraising, and strategy for the months leading to the November general election, which saw broader Democratic gains across the state.

Why the 2018 Primary Remains Relevant

Understanding the 2018 Illinois primary is useful for anticipating how nominations are shaped in a state with strong party leanings, high Democratic enrollment, and geographically distinct voting behavior. The primary clarified party preferences on issues such as economic policy, education funding, and state budget management, with candidates’ records and endorsements playing a central role. For ongoing analysis of Illinois elections, the 2018 cycle provides a baseline for comparing turnout, candidate quality, and electoral outcomes in future cycles.

Quick Reference: Key 2018 Illinois Primary Outcomes

• Date: March 20, 2018
• Governor nominee: J.B. Pritzker (D)
• U.S. Senate nominee: Tammy Duckworth (D)
• Attorney General nominee: Kwame Raoul (D)
• Comptroller nominee: Susana Mendoza (D)
• Secretary of State nominee: Jesse White (D)
• Treasurer nominee: Mike Frerichs (D)
• Republican Governor nominee: Bruce Rauner

Conclusion

The 2018 Illinois primary delivered a clear slate for the November general election, shaped by incumbency, party endorsements, and geographic voting patterns. Competitive statewide races, notably the U.S. Senate and gubernatorial contests, drew national attention and resources, while down-ballot primaries reinforced party slates. For observers interested in Illinois politics, the primary remains a reference point for understanding candidate pathways, party dynamics, and the conditions that drive electoral outcomes in a Democratic-leaning state.