Big Spending Reshapes Illinois Congressional Delegation in Primary

Over $125 million in campaign and outside group spending across five competitive races for open U.S. Senate and House seats in Illinois

Mar. 18, 2026 at 11:12pm

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In Tuesday's Illinois primary, Democrats ushered in a new generation of lawmakers, picking five new nominees for Congress in open seats that are favored to remain in Democratic hands this fall. However, it came at the end of a messy, expensive primary season, with around $70 million in spending from outside groups and $54 million in campaign spending across five competitive races for open U.S. Senate and House seats.

Why it matters

An unusually high number of retirements created opportunities for new representation up and down the ballot in Illinois, bringing in a flood of candidates and money. This level of spending is highly unusual for Illinois, a state better known for its machine politics than wide-open contests. The influx of outside money, particularly from crypto and AI-backed PACs, as well as groups with undisclosed donors, raises questions about the influence of special interests in shaping the state's political landscape.

The details

The Senate primary alone racked up more than $34 million in independent expenditures, with Lt. Gov. Juliana Stratton as the biggest beneficiary and target of outside spending. Rep. Raja Krishnamoorthi, who trailed Stratton by about 7 percentage points, spent nearly $24 million from his own campaign coffers. In four of the five contested primaries for open House seats, outside groups spent more than all the candidates combined, a highly unusual dynamic. The 9th District race saw over $10 million in outside spending, with the winner, Evanston Mayor Daniel Biss, getting support from groups like the Congressional Progressive Caucus PAC.

  • The Illinois primary election took place on Tuesday, March 18, 2026.
  • U.S. Sen. Dick Durbin announced last year that he would not seek a sixth term, prompting two House members to run for his seat.

The players

Juliana Stratton

The lieutenant governor of Illinois and the winner of the Democratic primary for the open U.S. Senate seat.

Raja Krishnamoorthi

A U.S. Representative who ran against Stratton in the Democratic Senate primary, spending nearly $24 million from his own campaign.

Daniel Biss

The mayor of Evanston who won the Democratic primary in Illinois' 9th Congressional District, with support from groups like the Congressional Progressive Caucus PAC.

Donna Miller

The Cook County Commissioner who won the Democratic primary in Illinois' 2nd Congressional District, boosted by over $4.3 million from the outside group Affordable Chicago Now.

JB Pritzker

The governor of Illinois, who provided at least $5 million to the Illinois Future PAC.

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What’s next

The winners of the Democratic primaries in Illinois are favored to win their general election races in the fall, ushering in a new generation of lawmakers in the state.

The takeaway

The high level of spending, particularly from outside groups with undisclosed donors, in Illinois' primary elections raises concerns about the influence of special interests in shaping the state's political landscape. This dynamic underscores the need for greater transparency and campaign finance reform to ensure that the democratic process remains responsive to the will of the people.