Rep. Rick Berg (R) conceded to former state Attorney General Heidi Heitkamp (D) in the North Dakota Senate race. It was the final outstanding Senate race of the the 2012 cycle.
This means that out of the seriously competitive Senate races, Republicans only won one Democratic-held seat. It also means that Democrats will have a majority of 55 Senators, including Sen. Bernie Sanders (I-Vt.), and assuming that Sen.-elect Angus King (I) of Maine will caucus with the party.
Republicans, who a year ago were expected to pick up seats and possibly the majority, actually lost 2 seats and will hold 45 seats in the 113th Congress.