Delaware has a single at-large representative in the House of Representatives. Republican incumbent Michael N. Castle was reelected for an eighth term. As of 2016, this is the last election in which a Republican was elected to congress in Delaware.
Primary elections in Delaware are closed primaries; that is, only voters who have declared a party affiliation may vote in that party's primary. Three Democrats were on the primary ballot: children's rights advocate and 2006 independent candidate Karen Hartley-Nagle, veterinarian and Vietnam War veteran Jerry Northington, and Michael Miller. Hartley-Nagle was nominated with 55.4 percent of the vote, with turnout at 28 percent. Castle did not face any Republican primary challengers.
Delaware Democratic Party House of Representatives primary, 2008
In the general election, Republican incumbent Michael N. Castle was challenged by Democratic nominee Karen Hartley-Nagle and Libertarian Party candidate Mark Anthony Parks. CQ Politics forecasted the race in Delaware's At-large congressional district as 'Safe Republican'. Castle enjoyed a lead throughout the campaign, and ultimately won the election with slightly over 61 percent of the votes cast. Statewide turnout for the election was at 68 percent.
Delaware's at-large congressional district election, 2008