A Republican, Lyon was elected to the Third District seat of the Kansas Senate in 2000. He defeated two Leavenworth residents to win the Republican nomination, and he beat Democratic nominee Mike Gibbens by somewhat more than 1,500 votes in the general election. In his term in the Senate, he served on four committees:
- Federal and State Affairs (of which he was the vice chairman)
- Joint Legislative Educational Planning
- Kansas Senate Republicans Archived 2007-08-08 at the Wayback Machine., Kansas Republican Party, 2004. Accessed 2007-08-20.
- Loads of candidates grace area ballots, The Topeka Capital-Journal, 2000-07-31. Accessed 2008-08-31.
- 2000 Kansas Official General Election Results, Secretary of State of Kansas, 2000. Accessed 2008-08-31.
- Kansas Senate Archived 2007-08-24 at the Wayback Machine., Kansas Senate, 2007. Accessed 2007-08-20.
- Minutes of the Synod and Yearbook of the Reformed Presbyterian Church of North America 2007. Pittsburgh: Crown & Covenant, 2008, p. 189.