Colorado State Senate seat · lines in effect since 2022
Colorado Senate District 15
A district of about 208,000 people, 51% of adults with a bachelor's degree. It votes D+7.7 relative to the nation for president.
Where it sits among all 35 seats
Every Colorado State Senate seat by partisan lean, from most Democratic to most Republican. Lean is the seat's presidential vote on current lines, relative to the nation.
Democratic
Source: 99chambers: 2024 and 2020 presidential results on current lines, relative to the nation (2024 weighted 3:1)Updated Oct 16, 2026, 5:19 AM ET
Every race on these lines
Results recomputed from precinct returns as if today's boundaries had always existed, so years compare like for like.
| 2016 | 2018 | 2020 | 2022 | 2026 | |
|---|---|---|---|---|---|
| U.S. Senate | R+1.9 | No race | D+2.7 | No race | No race |
| Governor | No race | D+4.8 | No race | No race | No race |
| Colorado State Senate | No race | No race | No race | D+1.2 | D+13.8 |
Outlined: the race for this seat itselfBlank: no race that year
Source: 99chambers results archive: precinct results allocated to current lines; 2026: Colorado Secretary of State and civicAPIUpdated Nov 7, 2026, 3:01 PM ET
Who lives here, compared
Grey bars show the spread of all 35 seats. Small marks are other seats in Colorado. The black marker is District 15.
Higher than 65% of seats.
Higher than 79% of seats.
Lower than 85% of seats.
Lower than 79% of seats.
Lower than 74% of seats.
Less dense than 79% of seats.
Source: Census Bureau, American Community Survey 2020–2024 5-year estimates, allocated to current linesUpdated Oct 13, 2026, 5:06 AM ET
Seats most like this one
Nearest seats on demographics, density and lean.
District 821% Hispanic · 45% college gradsD+10.6Held DDistrict 5
21% Hispanic · 42% college gradsR+0.1Not up in 2026District 12
43% college gradsD+4.1Not up in 2026District 6
22% Hispanic · 40% college gradsD+0.7Not up in 2026
Source: Census Bureau, American Community Survey 2020–2024 5-year estimates, allocated to current lines; 99chambers: 2024 and 2020 presidential results on current lines, relative to the nation (2024 weighted 3:1)Updated Oct 16, 2026, 5:19 AM ET
Who has held it
These lines took effect in 2022.
- Janice Marchman (D)
2023– · Won 2022 by 1.2, 2026 by 13.8
Source: Past results: 99chambers results archive (MEDSL, Klarner, state election offices)