Preview only: Colorado's own model is not built yet. The county groups, map, what-if scenarios and past-race numbers on this page are Texas's, used as stand-ins. The polls and results are Colorado's.
The forecast
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Numbers as a table
Things to know
The race in two minutes
Read by Maren Holt, Pollitrack's anchor · Recorded October 25
Read the transcript
I'm Maren Holt, and this is your Pollitrack digest on the Senate race in Colorado.
On November 3, Colorado decides who holds this seat for the next six years. On the ballot, in the order Colorado's drawing set: Republican Mark Baisley, who was unopposed in the June primary, and Democrat John Hickenlooper, the senator seeking a second term.
There is no public poll of this matchup yet. Until one arrives, the forecast starts from a stand-in drawn from Colorado's past results, with Hickenlooper ahead by 10. Colorado polls have understated Democrats in recent races, so the forecast moves that 1 point toward Hickenlooper. That leaves Hickenlooper ahead by 11, with a 99 percent chance of finishing first and Baisley at 1 percent.
Treat that with care. With no polls at all, the first one could move the forecast quickly in either direction.
Every active voter in Colorado gets a ballot in the mail. It can be mailed back or left at a drop box or a voter service center, and it must arrive by 7 pm on Election Day; a postmark does not count.
On election night, Pollitrack reads five bellwether counties, each standing in for a part of the state: Arapahoe, south and east of Denver, for the Denver metro and the ski towns; La Plata, home to Durango, for the suburbs and mountain towns, the biggest group; Fremont, home to Cañon City, for the Western Slope; Otero for Pueblo and farm country; and Yuma for the eastern plains.
Polls close at 7 pm Mountain. Counties post the mail ballots they counted early soon after, usually most of the vote, then the late drop-offs through the night. Scroll down to explore each county, or switch to What-if mode and play out your own night. I'm Maren Holt. See you on election night.
The recording plays on the Pollitrack site. The transcript is above.
Early voting
How to read this: the line adds up early votes day by day, in person and by mail. The amber line is 2026; the gray lines are past years on the same day of early voting, so a 2026 line above them means more early votes than then. Refreshed every morning and afternoon from the Colorado Secretary of State's early-vote counts.Numbers as a table
Numbers as a table
Cumulative early votes, in person and by mail, against the same day in 2022 and 2024.
In the news
How to read this: the headlines free news sources carry about this race, newest first, with who published each. The counts are how many stories named each candidate in the last seven days. Pollitrack reads the headlines; it does not judge them and they do not change the forecast.
The newest headlines about this race, refreshed twice a day.
This week: 1 story names Baisley, 6 name Hickenlooper, 3 name both.
- Hickenlooper Says “Playing Political Games” With Disaster Aid Is “Corrupt” — Insists Victims Deserve Help “No Matter Who They Voted For”
- Bob Chew spends big money on independent Senate campaign in Colorado
- Who is Bob Chew, the deep-pocketed independent U.S. Senate candidate in Colorado?
- Senator John W. Hickenlooper introduces S. 5587: National Critical Minerals Council Act
- 1-minute voter guide: Colorado's U.S. Senate race between Hickenlooper and Baisley
- Colorado Senate, House Candidates Debate Ahead of November’s Midterm Election
Five county groups
How to read this: every county joins the group whose bellwether county it has moved most like since 2016. The color is the group's margin in the view you pick: where its bellwether lands if the polls are right, its 2024 President result, or, on election night, how far each county has shifted since 2024. Darker means a bigger lead: 15 points or more, 5 to 15, or under 5. Tap a group or a county to light up its group.
Every county joins the bellwether it has voted most like since 2016.
Pick a group to light up its counties.
500 possible election nights
How to read this: the forecast is replayed 500 times, each with a different random draw of its uncertainty. Each dot is five possible nights, stacked by the statewide margin in 1-point steps: blue dots are Hickenlooper wins and red dots are Baisley wins. The more dots on one side of the tie line, the likelier that candidate wins.
The forecast replayed 500 times, with every county group free to miss.
Wins per 100 nights · each dot = 5 nights
The five bellwethers
How to read this: each row is one county, on a scale from a big Baisley lead (left) to a big Hickenlooper lead (right). The amber mark is the tie line: if every part of Colorado shifted as much as this county did, a result there would mean a statewide tie. A dot to the right of it is good news for Hickenlooper, and to the left for Baisley; the colored bar shows how far each county is from the tie line, and toward whom. The gray ticks are the 2024 and 2020 results. The dot is where the polling average points until results post, then the real result. Drag a dot, tap anywhere on a row, or use the arrow keys to try your own numbers; the dot clicks onto the marks when you get close.
Drag a dot, or pick a scenario, to see who wins Colorado.
Fine-tune the assumptions
County guides
Why each county was picked and what to watch.
Biggest vote source
ArapahoeTie line: Hickenlooper +9.1 · stands in for Denver, Aurora, Boulder, Adams County and the ski resorts, 37% of the vote
- 2024 President
- Harris +20.1
- 2022 Senate
- Bennet +22.8
- 2020 Senate
- Hickenlooper +19.3
- Compared with Colorado
- 7–11 points more Democratic in every race since 2016
Why this county
Arapahoe County (Aurora, Centennial and Littleton, south and east of Denver) leads eight counties that cast 37.0% of the 2024 vote, which Harris won by 35.6: Denver, Boulder and Adams, and the resort counties of Eagle, Summit, Pitkin and San Miguel. Arapahoe has tracked the group's swing most closely in the six races the model was tested on; Denver (1.0 points off on average) and Boulder (1.1) come close, and San Miguel and Adams are available as stand-ins.
What to look for
The tie line here is Hickenlooper +9.1: a result above it favors Hickenlooper, below it Baisley. Hickenlooper won Arapahoe by 19.3 in 2020, Bennet by 22.8 in 2022 and Harris by 20.1 in 2024. Denver's tie line is Hickenlooper +45.1 and Boulder's Hickenlooper +44.7. Adams moved the most here in 2024, from 2.8 points more Democratic than the state in 2020 to 2.0 less.
When results come in
All of Colorado closes at 7 pm Mountain. The page reads Arapahoe's count from the Secretary of State's results site as it posts; to watch Denver instead, pick it as the group's county.
Signals so far
Denver: . Colorado overall: . Colorado registers voters by party, and more of them are unaffiliated than either party. By October 22, Arapahoe had 71,706 ballots back: 26,057 from registered Democrats, 15,384 from registered Republicans and 29,459 from unaffiliated voters, by the Secretary of State's count. In June's primary Arapahoe cast 95,412 votes in the Democratic Senate race (Hickenlooper 55%, Julie Gonzales 45%) and 36,374 for Baisley, who was unopposed. For scale: Arapahoe cast 257,320 votes in the 2022 Senate race.
Western Slope test
FremontTie line: Baisley +49.4 · stands in for Grand Junction, Montrose, Cañon City, Elbert and Teller, 7% of the vote
- 2024 President
- Trump +38.4
- 2022 Senate
- O'Dea +27.4
- 2020 Senate
- Gardner +40.4
- Compared with Colorado
- 40–53 points more Republican in every race since 2016
Why this county
Fremont County (Cañon City and Florence, home of the state and federal prisons) leads ten counties that cast 6.7% of the 2024 vote, which Trump won by 31.4: Mesa (Grand Junction), Montrose and Delta on the Western Slope, Elbert and Teller near Denver and Colorado Springs, Las Animas (Trinidad), Custer, Dolores and Hinsdale. Fremont has tracked the group's swing most closely; Mesa (0.2 points off on average), Las Animas (0.2) and Delta (0.3) come close, and Montrose is available as a stand-in.
What to look for
The tie line here is Baisley +49.4: a wider Baisley margin favors Baisley, a narrower one Hickenlooper. Gardner won Fremont by 40.4 in 2020, O'Dea by 27.4 in 2022 and Trump by 38.4 in 2024. Mesa, the group's big county, has a tie line of Baisley +35.3.
When results come in
The page reads Fremont's count from the Secretary of State's results site as it posts; to watch Mesa instead, pick it as the group's county.
Signals so far
Mesa: . By October 22, Fremont had 6,211 ballots back: 2,508 from registered Republicans, 1,196 from registered Democrats and 2,458 from unaffiliated voters. In June's primary Fremont cast 7,534 votes for Baisley and 4,125 in the Democratic Senate race (Hickenlooper 61%). For scale: Fremont cast 19,988 votes in the 2022 Senate race and Mesa 73,440.
Suburban swing test
La PlataTie line: Hickenlooper +7.7 · stands in for Colorado Springs, Jefferson, Douglas and Larimer counties and the mountain towns, 45% of the vote
- 2024 President
- Harris +18.6
- 2022 Senate
- Bennet +21.8
- 2020 Senate
- Hickenlooper +14.4
- Compared with Colorado
- 4–8 points more Democratic in every race since 2016
Why this county
La Plata County (Durango, in the southwest corner) leads the biggest group: 19 counties that cast 44.9% of the 2024 vote, which Harris won by 5.8. They are El Paso (Colorado Springs), Jefferson, Douglas, Larimer (Fort Collins) and Broomfield, and the mountain counties from Garfield and Routt to Gunnison and Montezuma. Their voters are close to the state's middle, and their suburbs have moved toward Democrats since 2016. La Plata has tracked the group's swing most closely; Park (0.5 points off on average), Routt (0.5) and Broomfield (0.6) come close, and Jefferson is available as a stand-in.
What to look for
The tie line here is Hickenlooper +7.7: a result above it favors Hickenlooper, below it Baisley. Hickenlooper won La Plata by 14.4 in 2020, Bennet by 21.8 in 2022 and Harris by 18.6 in 2024. Jefferson's tie line is Hickenlooper +8.5 and El Paso's Baisley +20.8. These counties decide most of the statewide margin: a point of swing here is worth almost half a point statewide.
When results come in
The page reads La Plata's count from the Secretary of State's results site as it posts; to watch Jefferson instead, pick it as the group's county.
Signals so far
Jefferson: . El Paso: . By October 22, La Plata had 10,680 ballots back: 3,428 from registered Democrats, 2,127 from registered Republicans and 5,020 from unaffiliated voters. In June's primary La Plata cast 10,507 votes in the Democratic Senate race (Hickenlooper 58%) and 4,473 for Baisley. For scale: La Plata cast 29,729 votes in the 2022 Senate race and Jefferson 300,365.
Pueblo and farm country test
OteroTie line: Baisley +37.4 · stands in for Greeley, Pueblo, the Arkansas Valley and the San Luis Valley, 11% of the vote
- 2024 President
- Trump +26.4
- 2022 Senate
- O'Dea +12.5
- 2020 Senate
- Gardner +24.6
- Compared with Colorado
- From 16 points more Republican in 2016's Senate race to 37 in 2024's presidential race
Why this county
Otero County (La Junta and Rocky Ford, on the Arkansas River) leads 17 counties that cast 10.5% of the 2024 vote, which Trump won by 19.5: Weld (Greeley), Pueblo, Morgan (Fort Morgan), the San Luis Valley (Alamosa, Conejos, Costilla, Rio Grande, Saguache), Huerfano, Moffat, Rio Blanco and the lower Arkansas Valley. What they share is the direction they have moved: further from the state toward Republicans in each presidential race since 2016. Otero has tracked the group's swing most closely; Pueblo (0.4 points off on average), Saguache (0.4) and Moffat (0.5) come close, and Alamosa is available as a stand-in.
What to look for
The tie line here is Baisley +37.4: a wider Baisley margin favors Baisley, a narrower one Hickenlooper. Gardner won Otero by 24.6 in 2020, O'Dea by 12.5 in 2022 and Trump by 26.4 in 2024. Pueblo's tie line is Baisley +16.1 and Weld's Baisley +31.9. Whether the 2024 move holds in a midterm is the question this group answers.
When results come in
The page reads Otero's count from the Secretary of State's results site as it posts; to watch Pueblo instead, pick it as the group's county.
Signals so far
Pueblo: . Weld: . By October 22, Otero had 2,397 ballots back: 1,022 from registered Republicans, 635 from registered Democrats and 709 from unaffiliated voters. In June's primary Otero cast 2,083 votes for Baisley and 1,600 in the Democratic Senate race (Hickenlooper 62%); Pueblo cast 13,275 for Baisley and 22,882 in the Democratic race. For scale: Otero cast 7,236 votes in the 2022 Senate race and Pueblo 67,352.
Eastern plains test
YumaTie line: Baisley +76.4 · stands in for the eastern plains, from Sterling to Springfield, and North Park, 1% of the vote
- 2024 President
- Trump +65.4
- 2022 Senate
- O'Dea +59.1
- 2020 Senate
- Gardner +72.8
- Compared with Colorado
- 50–82 points more Republican in every race since 2016
Why this county
Yuma County (Yuma and Wray, on the Nebraska and Kansas lines) leads ten farm and ranch counties that cast 1.0% of the 2024 vote, which Trump won by 64.2: Logan (Sterling), Kit Carson, Washington, Lincoln, Phillips, Baca, Cheyenne and Kiowa on the eastern plains, and Jackson (North Park). The counties swing together almost exactly: any of them stands in for Yuma within a quarter point. Cheyenne, Jackson, Logan and Kit Carson are available as stand-ins.
What to look for
The tie line here is Baisley +76.4: a wider Baisley margin favors Baisley, a narrower one Hickenlooper. Gardner won Yuma by 72.8 in 2020 and Trump by 65.4 in 2024. Yuma casts about 4,500 votes, so a few hundred ballots move its margin; Logan, the group's biggest county, has a tie line of Baisley +67.6. Every point of swing in this group is worth a hundredth of a point statewide, so it matters most as a check on the others.
When results come in
The page reads Yuma's count from the Secretary of State's results site as it posts; to watch Logan instead, pick it as the group's county.
Signals so far
Logan: . By October 22, Yuma had 1,013 ballots back: 627 from registered Republicans, 87 from registered Democrats and 290 from unaffiliated voters. In June's primary Yuma cast 1,942 votes for Baisley and 328 in the Democratic Senate race. For scale: Yuma cast 3,967 votes in the 2022 Senate race and Logan 8,263.
Timeline
When results usually arrive, Mountain time.
Ballots by mail, and voter service centers. Colorado mails a ballot to every active voter: county clerks began mailing them on October 12, and voter service centers opened for in-person voting and same-day registration on October 19. Ballots can be mailed back or left at a drop box or a voter service center, and must arrive by 7 pm on Election Day; a postmark doesn't count. By the end of October 22, 730,614 ballots had come back, by the Secretary of State's count. This page tracks the returns county by county, against the same day of 2024 and 2022.
Polls close statewide at 7 pm Mountain. Anyone in line by 7 pm can still vote. Counties post the mail ballots they counted before Election Day soon after, usually most of the vote, then the ballots dropped off in the last days, through the night and the next days; this page reads each county's count every few minutes. Judge the night by the bellwethers against their tie lines (La Plata's is Hickenlooper +7.7, Arapahoe's Hickenlooper +9.1), not by the running total.
Counting the rest, and the county canvass. Voters whose ballot signature didn't match have until November 11 to fix it, the same deadline for ballots from military and overseas voters. Each county's canvass board then approves its results, by November 20.
State certification. The Secretary of State certifies the results in early December (December 6 in 2024). A race decided by half a percent or less of the winner's vote goes to an automatic recount (C.R.S. 1-10.5-101). The page doesn't model a recount.
Times are Mountain time. Counties post the mail ballots they counted before Election Day soon after polls close, then the late drop-offs through the night. The method in six steps, then its track record on past races.
- All 64 counties are grouped by how they have moved relative to the statewide margin across eight statewide races (2016–2024). Each group is tied to one bellwether county.
- When a bellwether reports, its change from its 2024 President margin (Harris vs. Trump) is applied to every county in its group, and each group is weighted by its share of the vote.
- Early-vote readings are moved toward the expected final count. That uses only the 2026 Election Day tilt (Colorado doesn't publish past results split by vote type), scaled by how much is still uncounted. Counties not yet in borrow the average change of those that are, pulled slightly toward the polls.
- Uncertainty combines the minimum uncertainty, how much of each county is still uncounted, and which counties haven't reported. The win chance and the 500 simulated nights both come from that.
- Until results post, the forecast is the polling average minus an allowance for how Colorado polls have leaned (1 point off Baisley unless you change it), with a 5-point spread, the typical size of a final Colorado poll-average miss since 2018. Where early votes are coming from trims nothing off it by default: each point the early electorate leans more Democratic than at the same point in 2024, measured by county, counts for the weight you set under "Fine-tune the assumptions", and in 2022 and 2024, measured against the election two years earlier, that lean did not predict how the polls missed. The five counties only start to matter on election night.
- Scheduled jobs in the cloud pull a Wikipedia poll table and the Secretary of State's ballot-return reports every morning and afternoon and, on election night, the Secretary of State's county results every few minutes, and write to this page's data store, which updates open copies of the page without a reload. No poll of the general election has been published yet, so the average stands in with the 2024 presidential margin.
Track record: past races predicted from these five counties alone
| Race predicted | Baseline race | Actual | Model | Miss |
|---|
These misses flatter the model. The five counties were picked by searching for the set that best fits these same six races. Tested on races it had not seen, the same search missed by about 0.7 points.
What's different in 2026
The model is built on 2016–2024. Here is what could make this race break from those patterns, and how the model handles each.
| Factor | What it could do | How the model handles it |
|---|---|---|
| An incumbent against a state senator | John Hickenlooper, Denver's mayor and then a two-term governor, won the seat in 2020, beating Cory Gardner by 9.3 points, and won June's Democratic primary with 52.8% over state Sen. Julie Gonzales. State Sen. Mark Baisley was unopposed for the Republican nomination. Four minor-party candidates are also on the ballot. | Before results, the forecast is the polling average less Colorado's allowance. The starting point for every county is the 2024 presidential race (Harris +11.0), so each county's swing measures how much better or worse Hickenlooper runs than Harris did there. |
| No polls of the race | No public poll of Hickenlooper against Baisley had been published by October 24. The only polls of the race were of June's Democratic primary. | Until a poll comes out, the page's polling average is a stand-in: the 2024 presidential margin, Harris +11.0, with the allowance added back, so the forecast before results is that margin. Colorado's final poll averages, taken the way this page takes them, understated the Democrat in four of the six statewide races since 2018: by 6.9 and 6.1 points in the 2022 governor's and Senate races, 2.3 in the 2018 governor's race and 0.9 in the 2020 presidential race. They overstated Hickenlooper by 1.5 in 2020 and Harris by 2.3 in 2024. On average Colorado's polls have leaned 2.1 points toward the Republican; pooled with the other states' midterm-year misses, that gives the default of -1 point: an allowance of 1 point taken off Baisley. The spread around it is 5 points, and the allowance is adjustable under "Fine-tune the assumptions." |
| An all-mail state | Every active voter gets a ballot in the mail; in 2024, 92% of voters sent theirs back by mail or drop box and 8% voted in person. Counties count mail ballots as they arrive, so the first results soon after 7 pm hold most of the vote, and the ballots dropped off on the last days come after. | Colorado's past results give each county's total only, not mail and in-person counts, so there is no county-by-county record of how the count moves through the night. The page uses its default spread for the move from first results to the final count, and the "How much more Republican Election Day votes will be" setting starts at zero. On election night the page reads each county's count from the Secretary of State's results site. |
| An open governor's race on the same ballot | Jared Polis can't run again. Attorney General Phil Weiser is the Democratic nominee for governor and Victor Marx the Republican one. Polis won by 19.4 in 2022 and 10.6 in 2018. | Voters who split their tickets show up in the Senate margins directly. In What-if mode, enter Senate margins, not governor's race margins. |
| Suburbs one way, Pueblo the other | Colorado went from Clinton +4.9 in 2016 to Biden +13.5 in 2020 and Harris +11.0 in 2024. Douglas and El Paso counties, south of Denver, moved toward Democrats against the state (Douglas from 23 points more Republican than the state in 2016 to 18 in 2024); Pueblo, Weld and the San Luis Valley moved toward Republicans (Pueblo from 5 points more Republican than the state to 16). | Pick a turnout pattern under "Fine-tune the assumptions" ("Like 2022" or "Like 2018"). The "2020 again" what-if replays each group's swing from Hickenlooper's own 2020 race. |
- County returns 2016–2024: the Colorado Secretary of State's historical elections database (official results by county for each contest). The counties add up to the official statewide count exactly.
- County boundaries: us-atlas (Census cartographic boundaries)
- Ballot returns: the Secretary of State's daily ballot-return reports (returned ballots by county and party, mail and in person; 2024 and 2022 from the same reports)
- Polling average: Wikipedia, 2026 United States Senate election in Colorado (poll table; none of the general election yet)
- Election-night results: the Secretary of State's results site, each county's count as it reports (the U.S. Senate and U.S. House races).
- In the news: headlines and links from Google News, GDELT and the state's own news outlets, read twice a day. Pollitrack never fetches or stores the articles themselves.