From 2003 to 2009, Johnson represented the 15th Senate district, encompassing rural Larimer County and the cities of Loveland and Estes Park.

In addition to his work on the six-member Joint Budget Committee preparing the state budget, Johnson has expressed priorities of expanding funding to higher education and re-opening the state drivers' license office in Loveland.

In June 2007, Johnson — otherwise healthy and athletic, having recently taken second place in a legislative fitness challenge — suffered a heart attack.

Since then, Johnson has placed a renewed emphasis on affordable healthcare, calling it a "moral issue" for the Republican Party.

[8][9] In January 2008, Johnson, facing the end of his senate tenure in 2010, announced his candidacy for a seat on the Larimer County Board of Commissioners.