Billionaire investor Warren Buffett has contributed $100,000 to Democrat Chuck Hassebrook in the Nebraska governor's race.

The contribution was disclosed Tuesday through Hassebrook's filing with the Nebraska Accountability and Disclosure Commission. Hassebrook, a former University of Nebraska Regent and director of the Center for Rural Affairs, is running against Republican Pete Ricketts, an Omaha businessman.

Buffett, the chairman of Omaha-based Berkshire Hathaway, contributes most often to Democratic candidates. A spokeswoman for Buffett says he made the contribution because he believes Hassebrook would make ``an outstanding governor.''

Buffett wrote a $2,500 check to Hassebrook when he ran for U.S. Senate in 2012, but the check was returned when former Democratic U.S. Sen. Bob Kerrey entered the race and Hassebrook dropped out.