博·拜登
Biden's son Beau Biden, the state Attorney General, considered entering the race but decided not to. Democrat Chris Coons, the county executive of New Castle County, entered the race instead and won the Democratic nomination unopposed. In a widely publicized Republican primary, Michael Castle, the former governor and nine-term U.S. Representative for Delaware's sole congressional seat who was initially heavily favored to win the primary and then the general election, was defeated in an upset by Tea Party movement-aligned marketing consultant Christine O'Donnell. Coons went on to defeat O'Donnell, as well as minor-party candidates Glenn A. Miller (Independent Party of Delaware) and James W. Rash (Libertarian), by a wide margin.