Through the years, he represented all or portions of Chippewa, Kandiyohi, McLeod, Meeker, Pope, Renville, Stearns and Yellow Medicine counties in the southwestern part of the state.

Notably, as Senate Minority Leader, Johnson cast a deciding vote in the passage of the 1993 Human Rights Act, which banned LGBT discrimination in housing, employment, and education.

[2][4] In March 2006, controversy arose over remarks Johnson made in January of that year to a group of pastors.

[5] When a tape recording of Johnson's remarks surfaced, the justices of the Minnesota Supreme Court denied that any such conversation had ever taken place.

This controversy contributed to the loss of his senate seat to Republican Joe Gimse in the general election that November.