Mary Kathryn "Heidi" Heitkamp (born October 30, 1955) is the junior United States Senator from North Dakota, in office since 2013, and a member of the North Dakota Democratic-Nonpartisan League Party. She was the 28th North Dakota Attorney General, serving from 1993 to 2001, and State Tax Commissioner from 1989 to 1993.Heitkamp was an unsuccessful candidate for governor in the 2000 gubernatorial election, losing to John Hoeven. She considered a bid for the Democratic nomination in the 2010 U.S.