In the 2004 general election, D'Amico was elected to the Illinois House of Representatives from the 15th district. After the election, 15th district Democratic incumbent Ralph Capparelli (who lost re-election in the 20th district) resigned effective November 4, 2004.
In the 2004 general election, D'Amico won a seat in the Illinois House of Representatives from the 15th district. Following his victory, Ralph Capparelli, the incumbent Democratic representative for the 15th district, resigned on November 4, 2004.