Who is Daniel Biss, the Democrat who narrowly beat Gen-Z star Kat Abughazaleh in Illinois

Daniel Biss, the mayor of Evanston and a former Illinois state representative and senator, narrowly defeated Gen-Z candidate Kat Abughazaleh in Tuesday’s Democratic primary for Illinois’ 9th Congressional District, emerging from a race that tested generational divides inside one of the country’s most reliably blue seats.

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Biss, 48, has long been a fixture in North Shore politics. A mathematician by training, he earned a Ph.D. from the Massachusetts Institute of Technology and later taught at the University of Chicago before entering public office. He served in the Illinois House and Senate from 2011 to 2019, where he built a reputation as a policy-driven progressive focused on campaign finance reform, voting access, and structural changes to government.

Mayor Daniel Biss addressed supporters after winning the Democratic primary for Illinoi's 9th Congressional District.CBS Chicago

He ran for governor in 2018 as an insurgent candidate but ultimately lost the Democratic nomination to now-Gov. J.B. Pritzker. In 2021, Biss was elected mayor of Evanston, a city that has become a national touchpoint for progressive policy, including pioneering a local reparations program and advancing public financing of elections.

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As mayor, Biss has also taken visible stands on federal immigration enforcement. In December, he confronted U.S. Border Patrol chief Greg Bovino and federal agents during an operation in Evanston, approaching masked officers at a gas station as residents gathered and recorded the encounter. The two spoke briefly, with Bovino telling Biss his agents were there to “make your city safe” before leaving the scene, according to Chicago PBS affiliate WTTW.

U.S. Border Patrol Chief Gregory Bovino is confronted by Evanston Mayor and congressional candidate Daniel Biss as they stop at a gas station while on patrol on December 17, 2025, in Evanston, Illinois. Scott Olson/Getty Images

In the congressional primary, Biss leaned heavily on his governing record, presenting himself as an experienced hand ready to deliver at the federal level. His base in Evanston and the surrounding North Shore suburbs, along with longstanding relationships in Democratic political circles, helped anchor his campaign.

But his campaign was also shadowed in its final hours by a personal disclosure. On Tuesday, as voters were heading to the polls, Biss acknowledged what his campaign described as an “ill-advised” relationship with a former student from his time as a 26-year-old instructor at the University of Chicago in 2004, according to the Daily Northwestern. The woman, then 20, said the relationship raised concerns about power dynamics, though it began after the course had ended.

Related: Illinois Democratic candidate Kat Abughazaleh calls out DOJ indictment

Speaking after the race was called, Biss embraced his victory as both personal and ideological, thanking a crowded field of opponents and signaling unity moving forward. “This has been a heck of a race,” he said, calling the 15-candidate contest a reflection of a “pivotal moment” for the country. He thanked Abughazaleh and congratulated her on a well-run race, adding that he would look forward to working with her and others who ran for the nomination.

He also paid tribute to retiring U.S. Rep. Jan Schakowsky, calling her “the conscience of our district and the conscience of the Congress” and crediting her support as instrumental to his win.

Biss cast the outcome as a broader test for Democrats, urging a more confrontational posture in national politics. “Are we going to concede in advance or are we going to fight?” he said. “Are we going to double down on our progressive values or are we going to shrink away from protecting the most vulnerable?”

“The voters spoke clearly,” he added. “We’re going to stand up. We’re going to fight. We will not back down.”

He outlined an economic message centered on inequality, calling for “housing that’s affordable for all, childcare that’s accessible to all, health care that’s available to all,” and a tax system that asks the wealthiest to “pay their fair share.”

Biss, who is Jewish, also leaned into a defining foreign policy issue in the race, describing his stance on Israel and Gaza as rooted in both personal history and moral urgency. He spoke of Israel as a refuge for his Holocaust-survivor family while also calling “the oppression of the Palestinian people is an unacceptable stain on the world and on the Jewish people as well, and has to be ended."

He also targeted outside spending in the race, particularly from AIPAC-aligned groups, which backed state Sen. Laura Fine, who finished third behind Abughazaleh and Biss. The groups spent millions early attacking Biss before shifting in the final stretch to focus largely on Abughazaleh, including ads suggesting she held right-wing views and efforts to boost another progressive candidate, Bushra Amiwala.

“The Ninth District is not for sale,” he said. “So enough about AIPAC, may tonight be the last time I utter their name."

Abughazaleh, 26, a former journalist who gained a national following for her reporting on right-wing extremism, offered a sharp contrast to Biss. Her campaign energized younger voters and drew attention online, positioning the race as a choice between a new generation of political voices and an established Democratic figure. Ultimately, Biss bested her by four percentage points.

Throughout his career, Biss has supported LGBTQ+ rights, including marriage equality and nondiscrimination protections, while serving in the state legislature.

With the primary victory, Biss is now the favorite to win the seat in November in a district that has long been held by Democrats.

Watch Daniel Biss speak to supporters after his victory below.

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