DENVER (KDVR) — New data from the Colorado Secretary of State’s Office shows that more than half of Colorado voters are now registered as unaffiliated, meaning they are not registered with a political party.

With the primary election just weeks away, those voters will need to decide whether to participate in the Democratic or Republican primary.

Colorado operates under a semi-open primary system, allowing unaffiliated voters to choose which party’s primary they want to vote in. With unaffiliated voters now making up the majority of registered voters in the state, their choices will play a significant role in election outcomes.

According to the Colorado County Clerks Association, the trend has been building since 2004, with voters continuing to leave both the Democratic and Republican parties to register as unaffiliated.

While an unaffiliated voter’s ballot choices remain private, the party primary they participate in does become part of their public voter registration record.

Unaffiliated voters also face some limitations. They cannot participate in party caucuses and cannot sign petitions for party candidates.

“I think the largest reason why we have so many unaffiliated voters is because people are intensely unhappy with both political parties, and they don’t want to be a part of it,” Matt Crane, executive director of the Colorado County Clerks Association, said. “And now with the primaries, they really don’t have to make that choice. They can just vote and then move on and not have to worry about some of the baggage and garbage that comes with being a member of a political party.”

Election officials are reminding unaffiliated voters that they received two ballots in the mail: one for the Republican primary and one for the Democratic primary. Voters should return only one ballot. If both ballots are submitted, neither vote will be counted.

If an unaffiliated voter casts a ballot in-person, the clerk will ask them which ballot they would like to cast.

The Colorado County Clerks Association also reminded voters that ballots must be received by Election Day, with the exception of military and overseas voters. Voters planning to return their ballots by mail should send them by the Tuesday before Election Day, one week in advance, to ensure they arrive on time.