Daniel Biss, the former mathematician turned state legislator and current mayor of Evanston, won a Democratic primary Tuesday night to become the Democratic nominee for Congress in Illinois’ 9th Congressional District, succeeding longtime Rep. Jan Schakowsky (D-Evanston).

The district, a deep blue stretching from Chicago’s far north side, through Evanston, Skokie, Glenview, Northbrook and northwest to Crystal Lake and Algonquin, is expected to remain blue in November’s general election, with Tuesday’s primaries setting up a largely ceremonial general election in November, positioning Biss the district’s next member of Congress.

Biss, first elected mayor in 2021 after an unsuccessful run for Illinois governor in 2018, was the favorite to succeed Schakowsky from the campaign’s earliest days, long expected to jump into the race after Schakowsky announced last May she would retire after 14 terms in Congress.

The 9th District has not elected a Republican for generations, and assuming all remains as anticipated later this year, Biss, at 49 years old, will head to Washington in January, becoming the second consecutive Evanstonian to represent the district in Congress.

He defeated a field of 15 other Democrats, one of the busiest primaries nationwide that drew national headlines in the final weeks, which included political newcomer Kat Abughazaleh, who placed second, according to results as of Tuesday night, with about 25.6%.

State Sen. Laura Fine of Glenview placed third, according to results, placed in third, with about 20% of the vote.

Biss, reelected as mayor in 2025, is likely to remain in office as mayor through November, planning to resign his office after votes are certified after the general election, just days before a deadline that will trigger an April special election to select a new mayor to finish Biss’ term.

While Biss will still need to win in November, given the district’s long history as one of the bluest districts nationwide, a Republican upset is extremely unlikely, almost certainly setting up for Biss’ assent to Washington next January.

To fill his seat, the Evanston City Council will select one of its own as the acting mayor, who will serve until April 2027. A City Council member will need a ⅔ majority vote for a City Council member to be selected. None of the nine members have publicly indicated they’re interested in the role as of yet.

While Biss’ win encapsulates an achievement the Evanston mayor has eyed for years, it didn’t come easy, facing credible opposition from several candidates and outside groups that outraised him and sought to undermine his support. 

In total, over $9 million was spent on the race by outside lobbying groups, including over $1.4 million spent on ads opposing him. 

In November, Biss will face Republican John Elleson, who won the GOP nomination Tuesday over Paul Friedman and other candidates.

This story is breaking and may be updated.