The 2026 United States Senate election in Colorado will be held on November 3, 2026, to elect a member of the United States Senate to represent the state of Colorado. Democratic incumbent John Hickenlooper is seeking a second term. He is being challenged by Republican state senator Mark Baisley.
Primary elections were held on June 30. In the Democratic primary, Hickenlooper won the nomination with 52.8% of the vote over state senator Julie Gonzales. Baisely was the only candidate to receive at least 30% support from the Republican State Assembly, allowing him to advance to the primary unopposed.
Background While Colorado was once considered a swing state, it has shifted significantly to the left over the past decade and is now regarded as solidly Democratic at both the federal and state levels. Democrats currently hold all statewide offices, both U.S. Senate seats, and strong majorities in both chambers of the Colorado General Assembly, while the state's U.S. House delegation is evenly split. In 2014, Republican Cory Gardner narrowly defeated Democratic incumbent Mark Udall for the U.S. Senate. As the state continued trending Democratic, Gardner—then the only Republican holding major statewide office—lost his 2020 re-election bid to Democrat John Hickenlooper by a significant margin. In late 2024, Hickenlooper announced he would seek re-election but indicated that the campaign would be his final run for the Senate.
Democratic primary Candidates To move forward to the primary, candidates had to petition onto the ballot or achieve 30% or more at the Colorado Democratic Party State Assembly. John Hickenlooper was the only candidate to petition onto the primary ballot. All other candidates went through the State Assembly process. Julie Gonzales was the only candidate to achieve 30% or more. Nominee John Hickenlooper, incumbent U.S. senator Eliminated in primary Julie Gonzales, state senator from the 34th district (2019–present)
Eliminated at convention Karen Breslin, college professor, candidate for U.S. Senate in 2022, and candidate for in 2024 Jessica Williams
Withdrawn Brashad Hasley, software engineer Nichole Miner, college student A.J. Zimpfer, accountant
Endorsements
Fundraising Italics indicate a withdrawn candidate. Campaign finance reports as of June 10, 2026CandidateRaisedSpentCash on handJulie Gonzales (D)$869,056$642,852$226,205John Hickenlooper (D)$9,884,305$8,561,826$2,964,562Source: Federal Election Commission
Polling Poll source Date(s)administered Samplesize MarginJulieGonzalesJohnHickenlooper Other UndecidedColorado Community ResearchMay 17–28, 2026796 (LV)± 4.0%34%41%–25%Data for Progress (D)February 20–25, 2026739 (LV)± 4.0%13%45%4%37%
Results
Republican primary Candidates To move forward to the primary, candidates had to petition onto the ballot or achieve 30% or more at the Colorado Republican Party State Assembly. None of the candidates petitioned onto the primary ballot. All candidates went through the State Assembly process. Mark Baisley was the only candidate to achieve 30% or more.
Nominee Mark Baisley, state senator from the 4th district (2023–present) (previously ran for governor)
Eliminated at convention Amanda Calderon, business owner Janak Joshi, former state representative from the 16th district (2011–2017) and candidate for Colorado's 8th congressional district in 2024 George Markert, AI strategic advisor (running for lieutenant governor) Sean Pond, Montrose County commissioner
Declined Brandi Bradley, state representative from the 39th district (2023–present) Endorsements
Fundraising Campaign finance reports as of June 10, 2026CandidateRaisedSpentCash on handMark Baisley (R)$77,147$65,702$11,445Source: Federal Election Commission
Results
Independent candidates Candidates Declared Christopher Baum (Approval Voting) Bob Chew (Forward) Blake Huber (Libertarian) Adam Withrow (Unity)
Withdrawn Clinton Roosevelt Dale Joshua William Kuebler
General election Predictions SourceRankingAs ofThe Cook Political ReportSeptember 23, 2026Decision Desk HQOctober 2, 2026The EconomistOctober 3, 2026FiftyPlusOneOctober 3, 2026Fox NewsSeptember 22, 2026Inside ElectionsOctober 1, 2026RealClearPoliticsSeptember 24, 2026Sabato's Crystal BallSeptember 22, 2026Silver BulletinOctober 3, 2026Split TicketOctober 2, 2026
Fundraising Campaign finance reports as of June 30, 2026CandidateRaisedSpentCash on handJohn Hickenlooper (D)$10,285,376$9,843,588$2,083,870Mark Baisley (R)$138,597$88,913$50,021Source: Federal Election Commission
Results
Notes Partisan clients
See also 2026 Colorado gubernatorial election 2026 Colorado elections
References
External links Official campaign websites Mark Baisley (R) Bob Chew (FWD) John Hickenlooper (D)