Democratic Congresswoman Tammy Duckworth defeated Republican incumbent Mark Kirk for the U.S. Senate seat once held by President Barack Obama.
The Associated Press projected Duckworth the winner Tuesday night, a boon for Democrat hoping to take control of the U.S. Senate.
After taking the podium to Kelly Clarkson's "Stronger," Duckworth told supporters Kirk is an inspiration for overcoming adversity and the country should be grateful for his service.
"No matter who you voted for today, we are all in this together," she said.
Kirk faced an uphill battle against Duckworth for the Senate seat that was widely expected to change party hands. Democrats have had Illinois penciled in the "win" column for months as they mapped a strategy to win back control of the Senate. Kirk is only the second Republican to represent Illinois in the Senate in more than three decades.
Like some Republicans across the country, Kirk struggled with the rise of Donald Trump as the GOP’s presidential nominee.
Veterans’ issues weighed heavily throughout the race, as both candidates have served in the military. But each candidate has harshly characterized their opponent’s military experience in campaign ads.
Duckworth, a veteran who lost both legs when the helicopter she was co-piloting was shot down in Iraq, ran campaign ads about Kirk’s exaggerations of his military experience.
During a debate, Kirk made a controversial comment mocking Duckworth’s family history, saying, “I’d forgotten that your parents came all the way from Thailand to serve George Washington.”
Duckworth's mother is of Chinese descent, born in Thailand. The congresswoman, who was born in Bangkok, says her father first went to Southeast Asia while serving with the Marines in Vietnam.
Kirk apologized for the remark, but he lost two endorsements -- one from the Human Rights Campaign, a gay-rights group; and another from American for Responsible Solutions, a gun-control group led by former U.S. Rep. Gabby Giffords.
The Associated Press contributed to this report.