Colorado will elect a new governor in November, and at least a dozen candidates are currently in the running on both the Republican and Democratic sides.

This year, unaffiliated voters have reason to take early notice in the race to replace term-limited Governor John Hickenlooper — and not just because of the dizzying number of candidates. Thanks to an open primaries ballot measure passed in 2016, voters who aren’t registered to either major party will able to help choose nominees for the first time in June.

Proponents of the measure argued that opening up primaries to independents could give a boost to more moderate candidates and wrest some control from the hardcore partisans who cast a disproportionate number of primary votes.

In practice, though, the change adds a big unknown to an already wild race, with implications all the way down the ballot and even for the coffers of county governments. The cost of including Summit County’s roughly 9,000 independents in primaries this year is expected to come in at roughly $20,000, according to the Summit County Clerk and Recorder’s Office.

“What we’re all wondering is to what extent will unaffiliated voters take advantage of this change and participate, and that’s really and truly a wild card,” said County Commissioner Thomas Davidson, a Democrat. “Even when I talk to experts who do this for a living they say, ‘we don’t really know what’s going to happen.’”

Comparisons are hard to find. While many states have open primaries, none use mail-in ballots as extensively as Colorado, where voting for party nominees could add only a couple of minutes to a P.O. box trip. The question is whether the unprecedented convenience will matter.

“In other states that have opened up primaries, they have historically seen low participation rates from unaffiliated voters — but those states don’t mail out ballots,” Davidson said.

Unaffiliated voters are the largest and fastest-growing bloc in Colorado, making up 37 percent of the electorate. In Summit County, around 9,000 of 19,000 total voters are unaffiliated. In early June, they’ll all receive primary ballots for the first time.

Those voters will get ballots from both parties, each listing candidates for governor, attorney general and all the way down to small local races. Summit County Clerk and Recorder Kathy Neel, who told the Summit Daily on Monday that she is seeking a third term, will be on the Democratic ballot. (Neel ran as Republican when she was re-elected in 2014).

But if unaffiliated voters want to vote for Neel or any other Democrat in the primary, they won’t be able to vote for any Republicans. Though they will receive both ballots, those voters will have to pick which one to vote on — in other words, no double dipping.

“Unaffiliated voters are going to get both the Democratic and Republican primary ballots, but they can only vote once — you have to pick one or the other,” Neel said. “Those people aren’t used to getting primary ballots unless they asked for them … I think this might be a little bit of a rough primary.”

If an unaffiliated voter turns in Republican and Democratic primary ballots, both will be nullified, Neel said.

That could mean that high-profile races at the top of the ticket could decide which primary independents choose to vote in, and thus, which down-ballot candidates they would also be able to choose.

What that could mean for local candidates is unclear. In theory, though, a big controversy on either the Democratic or Republican side of a race could grab unaffiliated voters’ attention and prompt them to cast a disproportionate number of ballots for either party’s primary.

“If somebody just cared about the governor’s race and only voted for that and didn’t vote anything else, it could have an affect on the outcome if there were a lot of people that did that too and didn’t vote for local candidates,” Neel said.

In Summit County, where local election margins are small and primaries can be won by a handful of votes, that could change the strategic calculus for some.

“It certainly makes it harder for people further down the ballot to know how to engage with local unaffiliated voters, or even if they should try,” said Davidson, who is not up for re-election this year. “I would guess that most voters are thinking about Democrats versus Republicans at the top of the ticket versus locally, but maybe not.”