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Illinois Sen. Mark Kirk has announced he "cannot and will not" support Donald Trump for president, according to a statement released Tuesday. Kirk, who said last month he would support Donald Trump if he was the Republican nominee, decided to retract his endorsement of the mogul due in part to his comments regarding Mexican-American judge Gonzalo Curiel.

Kirk is one of the most vulnerable GOP senators this election cycle, as he is facing a Democratic challenger in Rep. Tammy Duckworth who has made a concerted effort to link Kirk to Trump.