Sabo was born of Norwegian immigrant parents in Crosby, North Dakota and in 1959 received a B.A. from Augsburg College in Minneapolis, Minnesota, later pursuing graduate studies at the University of Minnesota. A Democrat, he became a member of the Minnesota state house of representatives in 1960, later serving as minority leader (1969-72) and as house speaker (1973-78). During his tenure in the state house he served terms as president of the National Conference of State Legislatures and of the National Legislative Conference, and was a presidential appointee to the National Advisory Commission on Intergovernmental Relations.
He was elected to the U.S. House in 1978 and has successfully stood for re-election twelve times since then. During the 103rd Congress (1993-94) he chaired the House Budget Committee. In the present (107th) Congress he sits on the House Apprropriations Committee, and is the ranking member of that committee's Homeland Security subcommittee.
A Lutheran, Sabo is married and has two children and six grandchildren.