Mark Baisley

Mark Baisley (born 1955) is an American politician who is a state senator from Roxborough Park, Colorado. A Republican, Baisley represents Colorado's 4th Senate district. Previously, he represented Colorado House of Representatives District 39, which encompassed parts of Douglas County and all of Teller County. He is the Republican nominee in the 2026 U.S. Senate election in Colorado, challenging incumbent Democrat John Hickenlooper.

Background Baisley earned a bachelor's degree with dual degrees in computer information systems and business administration from Columbia College, Missouri in 1993. He currently works as the president of Slipglass, Inc., an engineering software firm.

Baisley was re-elected to the state house in 2020.

In 2022, Baisley ran for a seat in the Colorado State Senate. Specifically, he ran to represent Colorado's 4th Senate district. In the general election, he defeated his Democratic Party opponent, winning 60.84% of the vote.

In March 2025, Baisley announced his candidacy for the 2026 Colorado gubernatorial election. On January 5, 2026, he suspended his campaign for Governor and announced his candidacy for the 2026 United States Senate election instead. Baisely was the only candidate to receive at least 30% support from the Republican State Assembly, allowing him to advance to the primary unopposed. According to the election law organization States United Action, Baisley has promoted conspiracies theories and misinformation about the legitimacy of elections, especially the 2020 presidential election.

Electoral history