(Newser) – Illinois Republican Mark Kirk's chances of keeping his US Senate seat took a hit Thursday night when he made an ugly—and inaccurate—remark about his opponent's heritage during a televised debate. After Democratic US Rep. Tammy Duckworth, who was born in Bangkok to a Thai mother and an American father, said her family "has served this nation in uniform going back to the Revolution" and described herself as "a daughter of the American Revolution," Kirk responded: "I forgot that your parents came all the way from Thailand to serve George Washington," reports the Hill, which describes Kirk as the most vulnerable GOP senator up for re-election. His remark was followed by several seconds of awkward silence before the moderator moved on to the next question.

Duckworth's father is a World War II vet with ancestors who served in the Revolutionary War, and she is a US Army vet who lost both her legs when an RPG hit the helicopter she was piloting in Iraq in 2004, the Guardian notes. Kirk, who served as an intelligence officer in the Navy Reserve, has used a wheelchair since a stroke in 2012. One of the debate's lighter moments came when he quipped: "I think we both agree the next senator from Illinois should use a wheelchair," the Chicago Tribune reports. Kirk—who has described Donald Trump as a "malignant clown"—"unendorsed his party's presidential nominee and called him out in paid ads," Trump campaign manager Kellyanne Conway said in a tweet gloating over the debate gaffe. (Read more Tammy Duckworth stories.)

