The Republicans who have long sought to stop their party from participating in Colorado’s primaries, mainly out of opposition to how unaffiliated voters are now allowed to cast ballots in them, received a major boost late Tuesday when a federal judge ruled that the burden for opting out is unconstitutionally high.
U.S. District Court Judge Philip A. Brimmer found the requirement that 75% of the Colorado GOP or the Colorado Democratic Party’s central committee must support opting out of the primaries before it can happen “constitutes a severe burden on the major parties’ right to association and is therefore unconstitutional”
“The opt-out provision creates a severe burden on the party’s association right by making it highly unlikely that an opt out motion will succeed,” Brimmer wrote in response to a lawsuit brought by the Colorado GOP against the state.
The right to association is enshrined in the 14th Amendment of the U.S. Constitution.
The Colorado GOP filed its challenge to Colorado’s law letting unaffiliated voters participate in partisan primaries — Proposition 108, approved by voters in 2016 — in 2023.
At first, the party was represented by John Eastman, the discredited attorney who was the architect of President Donald Trump’s efforts to overturn the results of the 2020 election. Eastman no longer represents the party in the case.
A faction of Republicans, led by former state Rep. Dave Williams, who was the Colorado GOP’s chairman for two years starting in March 2023, has repeatedly tried to persuade their party’s central committee to opt out of Colorado’s primaries. But they have failed year after year because they’ve been unable to meet the 75% threshold, most recently last year.
When the committee voted last year, 44.57% of the total central committee membership (507 people) voted to opt out, but the 226 votes represented more than half of those present.
A majority of the Colorado GOP’s central committee, made up of a few hundred party loyalists, has supported opting out in many of the votes.
Brimmer did not say what threshold would be constitutional, but he wrote that “if a major party has a reasonable ability to opt out of the semi-open primary, the associational burden of Proposition 108 would not exist.”
Brimmer rejected the Colorado GOP’s effort to invalidate Proposition 108 entirely.
“The undisputed facts regarding primary elections in Colorado since the implementation of Proposition 108 show no harmful effects to the party,” he wrote. “The party cannot identify any nonpresidential primary election in Colorado where the outcome was changed by the participation of unaffiliated voters or where the candidate favored by the plurality or the majority of unaffiliated voters differed from the candidate favored by the plurality or the majority of party voters.”
The ruling won’t affect this year’s primaries. Proposition 108 requires that the opt out vote happen Oct. 1 in the odd-numbered year preceding partisan primaries.
But for 2028 in beyond, Brimmer’s decision opens the door for Republicans who oppose Proposition 108 to be successful in their opt-out vote attempts. That could reshape Colorado’s political landscape.
Opting out of the primaries would prevent unaffiliated voters — who now make up more than half of Colorado’s electorate — from helping decide on the party’s general election nominees, but it would likely also mean that the only way for a GOP candidate to advance to the general election is through the caucus and assembly process, which is notoriously chaotic and frequently not representative of voters’ opinions.
Frequently, the most partisan candidates do best in the caucus and assembly process, while more moderate candidates gather voter signatures to make the primary ballot.
Without a primary, Republicans candidates wouldn’t have the option of gathering voter signatures to bypass assembly. Signature gathering allows major party candidates to make the primary ballot, but it’s not a route to the general election.
The Colorado Secretary of State’s Office, which was the defendant in the Colorado GOP’s lawsuit, said Wednesday morning that it was disappointed in the ruling.
“Unaffiliated voters represent over half of Colorado’s voters and they deserve to have a voice in our primary elections,” John Magnino, a spokesperson for the office, said in a written statement. “Based on our reading, the court has not disturbed the plans in place for the upcoming June 2026 primary election. We are disappointed with this decision, and are evaluating next steps in consultation with the Attorney General’s Office.”
The Colorado GOP didn’t immediately respond to a message seeking comment.
The backers of Proposition 108 said they were reviewing the ruling.
“This decision tramples on the voting rights of a majority of Colorado voters, namely the independent voters,” Kent Thiry, the wealthy former CEO of the Denver-based dialysis giant DaVita who financed Proposition 108, said in a written statement. “Voters own elections, not the parties. Voters pay for the elections, not the parties. This terrible tunnel vision decision is yet another reason why Colorado should adopt a fully open primary where each Colorado voter can vote for whomever they want, independent of party. I am eager for this deeply flawed decision to be appealed.”
The Colorado Democratic Party has welcomed unaffiliated voters’ participation in their primaries and there’s been no concerted opt-out effort among its leaders.
Proposition 108 was approved by voters by 6.5 percentage points.
This is a developing story that will be updated.