Results: Democratic Rep. Sean Casten defeats Republican Mayor Keith Pekau in Illinois' 6th Congressional District election

• Rep. Sean Casten defeated Republican Keith Pekau in Illinois' 6th Congressional District.
• Casten became the first Democrat to represent the 6th Congressional District in decades when he won in 2018.

Democratic Rep. Sean Casten defeated Republican Keith Pekau in Illinois' 6th Congressional District.

Polls closed in the state at 8 p.m. Eastern Standard Time.

Illinois' 6th Congressional District candidates

Casten serves on the Science, Space, and Technology Committee, the Select Committee on the Climate Crisis, and is the vice chairman of the House Financial Services Subcommittee on Investor Protection, Entrepreneurship, and Capital Markets.

Prior to his time in Congress, he worked as a scientist, a clean energy consultant, and the chief executive officer of a corporation that focused on utilizing energy recycling technologies to reduce greenhouse gas emissions. In 2006, Casten co-founded Recycled Energy Development, which focused on recycling wasted energy and converting energy facilities to cleaner, more economic uses.

In Congress, Casten has focused on climate issues and clean energy.

Casten became the first Democrat to represent the 6th Congressional District in decades when he unseated longtime Republican incumbent Peter Roskam in 2018. He retained the seat for a second term when he defeated former state Rep. Jeanne Ives in 2020.

Pekau, Casten's challenger, is the mayor of Orland Park, Illinois. He is also a US Air Force veteran and a small business owner. Before getting elected mayor in 2017, Pekau served as a management consultant for two international consulting firms. He has also served as the state director of Vets4Energy, a nonpartisan citizens' coalition which focuses on energy policy and national security.

Pekau defeated his GOP opponents in the six-way primary, bringing in nearly 40% of the vote.

Voting history for Illinois' 6th Congressional District

Illinois' 6th Congressional District encompasses many of Chicago's southwestern suburbs and extends from Tinley Park to Lombard.

Joe Biden scored a 13-percentage-point margin of victory over President Donald Trump under the district's previous boundaries in 2020. The district shifted south to include more suburban communities in southwestern Cook County in redistricting following the 2020 Census, making it slightly less Democratic-leaning.

It's also the only district in the state where two Democratic incumbents ran against one another in the primary. Because of redistricting, portions of the districts represented by Casten and Rep. Marie Newman were squished together into the new 6th District, forcing them into a representative-on-representative face-off.

Casten handily defeated Newman, 68.1% to 28.8%.

The money race

According to OpenSecrets, Casten raised $5 million, spent $4.8 million, and had about $537,000 on hand, as of October 19. His opponent, Pekau, raised $1.25 million, spent $1.2 million, and had about $50,000 cash on hand, as of October 19.

As of late October, more than a dozen super PACs, national party committees, politically active nonprofits, and other non-candidate groups together spent about $1 million to advocate for or against candidates in this race, including during the race's primary phase.

What experts say

The race between Casten and Pekau was rated as "likely Democratic" by Inside Elections, "likely Democratic" by The Cook Political Report, and "likely Democratic" by Sabato's Crystal Ball at the University of Virginia Center for Politics.