Colorado is a Democratic-leaning state. Democrats hold the governorship, both U.S. Senate seats, every other statewide elected office, and majorities in both chambers of the state legislature, and the state has voted for the Democratic presidential nominee in five straight elections from 2008 through 2024. The picture is more textured than that headline suggests: the largest single bloc of registered voters belongs to neither party, and Republicans still win reliably in rural Colorado and in three of the state’s eight congressional districts.
Unaffiliated Voters Outnumber Both Parties
As of mid-2025, roughly half of Colorado’s active registered voters carry no party affiliation. Data reported by the Secretary of State in September 2025 put the unaffiliated share at 50.3%.1Axios Denver. Colorado Registered Voter Unaffiliated Democrat Republican July 2025 figures broke down to about 2.03 million unaffiliated voters, 1.04 million Democrats, and 936,000 Republicans.2Colorado Newsline. Colorado Voters Unaffiliated
Those numbers do not describe a 50-50 electorate. Political scientists and pollsters estimate that about 60% of Colorado’s unaffiliated voters lean Democratic.1Axios Denver. Colorado Registered Voter Unaffiliated Democrat Republican A late-2025 poll found 44% of unaffiliated respondents would pick a Democrat for Congress if the election were held that day, against 38% for the Republican. Among the same voters, 35% said they usually vote Democratic, 26% Republican, and 35% split their tickets.3The Colorado Sun. Colorado Unaffiliated Voters Poll
The size of the unaffiliated bloc is partly a quirk of the rules. Colorado runs a semi-open primary, so unaffiliated voters can participate in either party’s primary without registering, and Colorado State University political scientist Kyle Saunders has noted there is little practical reason for most voters to formally pick a party.1Axios Denver. Colorado Registered Voter Unaffiliated Democrat Republican
Five Straight Presidential Wins for Democrats
From 1920 through 2004, Colorado voted Republican for president in every election. That streak ended in 2008, and every race since has gone to the Democrat, usually by a comfortable margin.4270toWin. Colorado Presidential Voting History
- 2008: Barack Obama 53.7%, John McCain 44.7%.
- 2012: Obama 51.5%, Mitt Romney 46.1%.
- 2016: Hillary Clinton 48.2%, Donald Trump 43.3%.
- 2020: Joe Biden 55.4%, Trump 41.9%.
- 2024: Kamala Harris 54.2%, Trump 43.2%, on 79.5% turnout.5Colorado Newsline. Colorado Presidential Electors Cast Votes for Kamala Harris
By the 2024 cycle, the Cook Political Report classified Colorado as “Safe Harris,”4270toWin. Colorado Presidential Voting History and its Partisan Voter Index rated the state D+3 based on 2021 data.6Cook Political Report. Partisan Voter Index by State
Democrats Control State Government
Governor Jared Polis, a Democrat first elected in 2018, is serving his second term.7National Governors Association. Governor Jared Polis He won reelection in 2022 by about 485,000 votes over Republican Heidi Ganahl.8Colorado Secretary of State. General Election Results – Governor Attorney General Phil Weiser and Secretary of State Jena Griswold are also Democrats.9News From the States. Secretary of State Jena Griswold Will Run for Colorado Attorney General Democrats have won every statewide election over the last eight years by an average of more than 10 percentage points.10Colorado Newsline. Republican Candidates for Colorado Governor Debate
In the legislature, Democrats hold 23 of 35 state Senate seats and 43 of 65 state House seats, according to the National Conference of State Legislatures.11National Conference of State Legislatures. State Partisan Composition Those margins have allowed Democratic majorities to drive the agenda on housing, healthcare, gun policy, and climate.12Colorado Senate Democrats. Legislative Achievements
Congressional Delegation
Both U.S. Senate seats belong to Democrats: Michael Bennet and John Hickenlooper.13University of Colorado. Colorado Congressional Delegation Bennet won reelection in 2022 by nearly 15 points over Republican Joe O’Dea.14Politico. Colorado Senate Election Results
The U.S. House delegation is more divided. Democrats hold five of the eight seats and Republicans hold three heading into 2026.15270toWin. Colorado House Election Republican Gabe Evans flipped the 8th District in 2024 by unseating Democrat Yadira Caraveo.16The Hill. Republican Gabe Evans Flips Colorado 8 The split is geographic: Democrats represent Denver and the suburban Front Range, and Republicans represent rural and exurban districts.
How Colorado Turned Blue
Colorado’s shift from a reliably Republican state to a Democratic-leaning one played out over roughly two decades, driven by population growth along the Front Range, the corridor of cities and suburbs running from Fort Collins through Denver to Colorado Springs. About 83% of the state’s 5.4 million residents live in that corridor.17PBS NewsHour. Republicans Lost Suburbs
Growth in healthcare, telecom, and tech during the 1990s drew younger, more diverse, and more liberal residents into the suburbs. The state’s Hispanic population now exceeds 1.26 million, nearly 22% of the total, and Colorado’s diversity index rose from about 47% in 2010 to 52% by 2020.18The Colorado Sun. Colorado Census Population Growth Arapahoe County, a Republican stronghold from the 1960s into the early 2000s, voted for a Democratic presidential candidate for the first time in four decades in 2008.17PBS NewsHour. Republicans Lost Suburbs Jefferson County, long treated as a bellwether, backed Harris by more than 20 points in 2024.19Colorado Newsline. Lower Turnout Uneven Red Wave Colorado
Colorado’s population grew by nearly 15% between 2010 and 2020, roughly double the national rate, concentrated so heavily along the Front Range that the state picked up an eighth congressional seat after the 2020 Census.18The Colorado Sun. Colorado Census Population Growth
Where Republicans Still Win
Colorado is not uniformly blue. The state’s most conservative territory sits in the northeastern corner, where two state House districts covering the ranches and farmland along the Wyoming, Nebraska, and Kansas borders are considered the most conservative in Colorado.20CPR News. Most Conservative Place Northeast Colorado
Southern Colorado moved sharply toward Trump in 2024. Pueblo County, once a Democratic stronghold, went for Trump by almost five points, his best showing there yet. Four rural San Luis Valley counties shifted toward Trump by roughly 10 percentage points or more. Mesa and Montrose counties on the Western Slope remain heavily Republican. In slightly more than half of Colorado’s 64 counties, Trump’s 2024 vote share topped his 2020 share.19Colorado Newsline. Lower Turnout Uneven Red Wave Colorado
Those gains have not translated into statewide competitiveness because they are concentrated where few voters live. The rural counties trending rightward are sparsely populated, and several are losing population, while the dense Front Range suburbs that anchor Democratic margins keep growing.18The Colorado Sun. Colorado Census Population Growth Colorado Republicans have elected only one governor in the last 50 years.10Colorado Newsline. Republican Candidates for Colorado Governor Debate
So the short answer holds with the qualifier. Colorado is Democratic at the statewide and presidential level, and has been for a decade and a half. It is Republican in most of its geography and in three of its eight U.S. House districts. The half of the electorate that belongs to no party leans Democratic on average but splits its tickets often enough that individual races, especially in the swingier House districts, stay genuinely contested.