Proposition 131 Explained: Colorado's Open Primary and Ranked Choice Voting Proposal

One initiative on the ballot this November could change the way Coloradans vote in most future elections.

If approved by voters, Proposition 131 would overhaul Colorado's election system by eliminating most party primaries and replacing them with open primaries in which candidates of all (or no) political parties can participate and the top four vote-getters move on to the general election. Then during the general election, Prop 131 would implement ranked choice voting, where voters rank candidates by preference instead of choosing just one.

This proposal has big money behind it, and also a major split between big-name supporters and opponents.

Supporters say the measure would weaken the power of political parties, resulting in more moderate candidates who appeal to the general public rather than their base, while also making third-party candidates a more viable option for voters.

“In a state where nearly half of voters are independent, the current party-primary system limits voter choices and gives too much power to political insiders and special interests,” says Kent Thiry, chairman of the Yes on 131 campaign. “Prop 131 puts voters in charge, as any voter will have the right to vote for any candidate in every taxpayer-funded election, and candidates will need support from a majority of voters to be elected.”

However, opponents argue the measure would increase the role of money in politics, making it harder for non-wealthy candidates to succeed by removing the party pathway onto the ballot. They point out that the effort is being led by Thiry, a multi-millionaire who previously explored running for governor of Colorado, and funded by ultra-rich donors such as Walmart heir Ben Walton and Netflix co-founder Reed Hastings.

Senator Elizabeth Warren of Massachusetts, a former presidential candidate, spoke out against the ballot measure on October 25, criticizing its millionaire-backing as an effort "to tilt the political landscape toward their own special interests."

"Colorado, with its excellent existing system and strong voter turnout, should not be the guinea pig for interests pursuing their own experiments," says U.S. Senator Michael Bennet, a leading advocate against the measure. "We are being asked to throw out our excellent system without any persuasive reason to believe the new one will actually be better and with real risk that dark money will play an even more destructive role in our democracy."

Critics have also raised concerns that the new election system would be costly and difficult to implement, and discourage voter turnout by making voting more confusing.

Here's how it would work: Instead of the current primary system in which Democrats and Republicans each hold an election to select a candidate to represent their party in the general election, there would be one primary election featuring all candidates of all party affiliations, including third-parties and independents. The top four vote-getters of that all-candidate primary would advance to the general election, regardless of their party affiliation.

During the general election, voters would rank the candidates in order of their preference: first, second, third and fourth. If one candidate gets over 50 percent of the first-preference votes, that candidate wins. If no one gets the majority, then the candidate with the least first-preference votes is eliminated and those votes instead go to the voters' second-choice candidates. The process is repeated until one candidate reaches the 50 percent threshold.

This new election system would apply to Colorado’s races for Congress, governor, attorney general, secretary of state, treasurer, state board of education, CU board of regents and the state legislature. It would not apply to the presidential election or local races for district attorney, county commissioner or other offices.

While several states use different versions of ranked-choice voting or all-candidate primaries, Alaska is the only state with a system similar to the one Proposition 131 proposes, with an all-candidate primary advancing four candidates to a ranked-choice voting general election. Alaska's system was first used in 2022, and its results are disputed from both sides of the ballot debate.

"Right now, 93 percent of Colorado seats are competed in. In Alaska, 30 percent of the seats are single-party general elections," said Shad Murib, chair of the Colorado Democratic Party, while debating against the measure earlier this month. "I cannot imagine a worse way to provide for competition. ... This measure will make every problem we have in Colorado politics worse."

Critics emphasize that the proposed voting system has the potential to result in general elections where all four candidates are from one political party, while Colorado's current system at least guarantees the opportunity for a Democrat and Republican to face off.

But proponents of the ballot measure point out that the majority of Colorado's races are not competitive even if they are contested. Most districts are so heavily dominated by one political party that the minority party has little to no chance of winning the general election. That means the primary election, in which not all voters can participate and there is often low turnout, is the election that actually determines who will make it to office.

“Special interests control our politics because election rules allow them to hand-pick the party nominees — often leaving voters to choose between less desirable candidates,” says Toni Larson of the League of Women Voters, in defense of the measure. “Prop 131 puts the power in voters’ hands.”

The state Democratic and Republican parties are both opposing the measure, as are politicians including Congresswoman Diana DeGette, State Treasurer David Young, ten state senators, 25 state representatives and five Denver City Council members. Groups against the measure include the Colorado Education Association, Colorado Fiscal Institute, New Era Colorado and Western Colorado Alliance.

Backers of the initiative include Governor Jared Polis, U.S. Senator John Hickenlooper and the mayors of Denver, Aurora, Colorado Springs, Fort Collins, Broomfield, Grand Junction, Norwood, Rifle, Ridgway and Cortez. Organizations supporting it include the Colorado Chamber of Commerce, League of Women Voters, Veterans for Colorado Voters and American Enterprise Institute.

Election Day is November 5; keep an eye on our Election topic page for all of our latest coverage.