Colorado · Senate

Who is running?

John Hickenlooper (Democratic), Mark Baisley (Republican), Adam Withrow (Unity), Blake Huber (Libertarian), Bob Chew (Forward), Christopher Baum (Approval Voting).

The race, in brief

Colorado elects a U.S. senator on November 3, 2026. The text says the state, once a swing state, is now regarded as solidly Democratic: Democrats hold all statewide offices and both Senate seats, while the U.S. House delegation is evenly split. The state profile on file records a college share of 0.4 and a Hispanic share of 0.2.

Democratic incumbent John Hickenlooper, who defeated Republican Cory Gardner in 2020 by what the text calls a significant margin, is seeking a second term and has said it will be his final Senate run. He won the June 30 primary with 52.8% to state senator Julie Gonzales's 47.2%. The Republican nominee is state senator Mark Baisley of the 4th district, the only Republican to reach 30% at the state assembly, who then ran unopposed. Libertarian, Forward, Unity and Approval Voting candidates are also standing.

All ten raters listed call the race D, with dates from September 17 to September 26, 2026. As of June 30, 2026 Hickenlooper had raised $10,285,376 with $2,083,870 on hand; Baisley had raised $138,597 with $50,021 on hand. The text lists no general-election polls.

A paragraph quoting a model forecast from the day this brief was written is omitted; the current forecast is at the top of this page.

The facts, each beside its sentence

Not in the source: facts.forecast is empty: no model nowcast or election-day row for this race.; facts.candidates marks Hickenlooper incumbent: false, but the text says he is the incumbent.; No general-election polls (Hickenlooper vs. Baisley) in the text.; No 2020 Senate margin or presidential results are given as numbers.; Rater calls are given only as 'D', with no Lean/Likely/Safe detail.; The text spells the nominee 'Baisely' once in the lede.

Read from the district's section of Wikipedia's state page (CC BY-SA), archived as 3ac8ce1ae5cb; written by claude-opus-5-5 (batch reader) on 2026-09-30 and checked mechanically: every quote occurs verbatim in the archived text, every number in the brief occurs in the inputs. No probability here is the reader's.

Who holds the seat now

Michael F. Bennet (Democrat), in this chamber since 2009, 4 terms, class 3 (term ends 2029). Committees: Senate Committee on Agriculture, Nutrition, and Forestry; Senate Committee on Finance; Senate Committee on Rules and Administration; Senate Select Committee on Intelligence.

John W. Hickenlooper (Democrat), in this chamber since 2021, 1 term, class 2 (term ends 2027). Committees: Senate Committee on Commerce, Science, and Transportation; Senate Committee on Energy and Natural Resources; Senate Committee on Health, Education, Labor, and Pensions; Senate Committee on Small Business and Entrepreneurship.

From the congress-legislators dataset (CC0), archived as ae8cb9477c48. For a Senate race this lists both of the state's senators; the one whose term ends in the election year holds the seat on the ballot. For a House district redrawn for 2026 it is the member elected under the old lines with this number, who may be running elsewhere; the dossier above names who is running here.

The money

FEC bulk candidate summaries through July 17, 2026; $862,672 of independent expenditures for or against these candidates this cycle (FEC Schedule E, types 24E and 24A), which is the parties' and outside groups' own revealed view of whether this seat is in play.

How it has voted for president

A shift of 5.9 points toward the Democrats from 2016 to 2024. county returns summed; MEDSL county file (2016), an MIT-licensed county file (2020, checked against certified state results) and MEDSL precinct returns (2024). For a district split across counties this is an estimate, and where the state published the exact 2024 figure for these lines, that exact figure is the one the model uses.

The state in numbers

ACS 5-year state tables; BLS county unemployment and BEA county income, transfers and jobs summed to the state. Every figure is a named column of a named public-domain table, archived before it was read.

Has anyone polled it?

We hold no published poll of this general election. A search of aggregators, pollster releases, university polls and local news on 2 October found none (primary polls exist for some races and are not this contest). That is what we could find, not proof that no poll has been conducted. When one is published it enters the poll model and this page gains a nowcast.

Who is ahead, and by how much?

Margins and probabilities are for John Hickenlooper. With no polls, this is the fundamentals forecast alone: the state's own past results for this office and for president, its demographics, economy, religion and government employment, the candidates' incumbency, experience and money, and the national environment for this midterm.

How wide is the range?

In 8 of 10 simulations the margin falls between +9 and +44 points. The spread is the fundamentals model's own measured error (sd 13.4 points), not a guess: a forecast without polls is uncertain and is shown that way.

How accurate is a fundamentals-only forecast?

Tested on past races without letting it see them: across 175 Senate and governor races in 2016-2022 it missed the final margin by 8.3 points on average, and by 6.7 points across 35 races in 2024. Our poll-based forecast missed by 5.4 on the same races. Most races it is used for here are lopsided enough that an 8-point miss would not change the winner.

Where did every number come from?

Run 37983c0c, single_race_latent/0.8.1, as of 2026-10-01 23:02 UTC, basis: ground-up prior only, no polls.