Sen. John Hickenlooper, a Democrat first elected in 2020, is running for a second term against Republican state Sen. Mark Baisley of Woodland Park.
Political forecasters such as the Cook Political Report and Sabato’s Crystal Ball rate the seat as solidly Democratic, and Hickenlooper has roughly 40 times more cash on hand than Baisley. Even so, control of the Senate is at stake nationally: Republicans currently hold 53 seats to Democrats’ 47, and Democrats need to flip four seats to take the majority.
This is a separate race from the gubernatorial contest. Sen. Michael Bennet, who ran for governor and lost his primary to Attorney General Phil Weiser in June, holds Colorado’s other Senate seat and isn’t up for reelection until 2028.
Who’s running
John Hickenlooper (D), 74, founded Denver’s Wynkoop Brewing Co. before serving as Denver’s mayor from 2003 to 2011 and Colorado’s governor from 2011 to 2019. He said in August 2024 that this will be his last Senate campaign as he will not seek a third term. He beat progressive state Sen. Julie Gonzales in the June 30 Democratic primary, 53% to 47%.
Mark Baisley (R), 70, spent his career in aerospace and defense technology, including work for NASA’s Jet Propulsion Laboratory, before entering the state legislature in 2019 and has represented Douglas County in the state Senate since 2023. He switched from the governor’s race to the Senate race in January and won the Republican nomination unopposed in April.
Where they stand
Affordability and the economy
- Hickenlooper blames the Trump administration’s tariffs for squeezing household budgets and says he’d work to roll back tariffs he calls illegal.
- Baisley wants to cut federal taxes and regulations and expand domestic energy production to lower costs.
Health care
- Hickenlooper supports universal health care and wants Medicare to negotiate all drug prices, instead of the 10 currently permitted.
- Baisley opposes what he calls “government control” of health care, and favors expanding health savings accounts and price-transparency rules.
Immigration
- Hickenlooper condemns Immigration and Customs Enforcement’s (ICE) “lawlessness” and calls for ICE to be “completely overhauled or shut down.”
- Baisley backs stricter enforcement and sponsored a state bill directing cooperation with federal immigration enforcement.
Guns
- Hickenlooper’s Senate voting record supports gun-control measures like background-check expansions; he is calling for universal background checks and an assault weapons ban, as per his campaign website.
- Baisley has publicly praised a US Department of Justice lawsuit challenging Colorado’s ban on large-capacity ammunition magazines, calling it a step toward restoring Second Amendment rights.
Abortion
- Hickenlooper supports abortion rights, consistent with his Senate voting record, and expanded access to free birth control as governor.
- Baisley has consistently voted against abortion-rights protections in the state legislature, including Colorado’s Reproductive Health Equity Act.
Worth noting: Baisley told a religious-conservative conference in September 2025 that LGBTQ colleagues in the legislature were in what he called “rebellion against the nature of God,” remarks reported by multiple outlets.
Money and endorsements
Hickenlooper has raised roughly $8 million this cycle, with $2 million on hand. Baisley has raised roughly $135,000 total, with about $50,000 on hand.
Baisley is endorsed by GOP members of Colorado’s congressional delegation, including Rep. Lauren Boebert (R, Windsor), Rep. Gabe Evans (R, Fort Lupton) and Rep. Jeff Crank (R, Colorado Springs). Baisley has not received a formal endorsement from President Donald Trump.
Hickenlooper is endorsed by Colorado’s other senator, Michael Bennet (D, Denver), and Democratic members of Colorado’s congressional delegation, including Rep. Brittany Pettersen (D, Lakewood), Rep. Jason Crow (D, Aurora) and Rep. Joe Neguse (D, Lafayette).
How to vote
Every active registered Colorado voter gets a mail ballot no later than 18 days before Election Day. Register by Oct. 26 to get one mailed; same-day registration is available in person through Nov. 3. Ballots must reach your county clerk by 7 p.m. Nov. 3, regardless of when it was postmarked.
