A federal judge has ruled that Colorado's 2016 ballot initiative, Proposition 108, makes it too difficult for political parties to close primaries to unaffiliated voters. This ruling represents a significant victory for conservatives within the state Republican Party. The law requires a high threshold for parties to temporarily close their primaries to exclude unaffiliated members, requiring three-quarters of their central committee to vote in support. The ruling does not set a new threshold for these parties to set. The state GOP filed a lawsuit against the Colorado Secretary of State’s Office in 2023 under the leadership of conservative hardliner Dave Williams, who argued that closing primaries was vital to protecting true Republican candidates.