After Democratic Congresswoman Tammy Duckworth described herself as a “daughter of the Revolution” during the second of three debates in the Illinois U.S. Senate race, incumbent Republican Mark Kirk replied, “I forgot that your parents came all the way from Thailand to serve George Washington.” Duckworth, who served as a U.S. Army helicopter pilot and lost both legs fighting in the Iraq War, was born in Thailand to a Thai mother and an American father, who traces his roots back to before the Revolutionary War. Kirk, who unendorsed Donald Trump in June following his remarks about a Mexican-American judge, trails Duckworth by an average of 7 percentage points in the polls.

Following the debate, the Kirk campaign issued a statement, but not an apology. “Sen. Kirk has consistently called Rep. Duckworth a war hero and honors her family’s service to this country,” it read. “But that’s not what this debate was about. Rep. Duckworth lied about her legal troubles, was unable to defend her failures at the VA, and then falsely attacked Sen. Kirk over his record on supporting gay rights.”

Duckworth responded on Twitter with a photo of her family.

UPDATE—Friday, Oct. 28, 12:30 p.m. ET: Kirk apologized, tweeting, “Sincere apologies to an American hero, Tammy Duckworth, and gratitude for her family’s service.”