The single biggest group of voters in Colorado are people who want nothing to do with either major political party. Independent voters now vastly outnumber Republicans and Democrats here.

Many are under the age of 35, the millennial generation. Colorado has 2nd fastest growing millennial population in the country, and, by far, the most as a proportion of the population of any swing state.

To get a sense of their political power, in 2012, more Republicans voted than Democrats in the presidential election here, so Mitt Romney should have won.

“But as it was, the unaffiliated probably washed out that difference and then created the winning margin for Obama,” according to Judd Choate who runs the elections division for the Colorado Secretary of State’s office.

That winning margin was thanks in part to voters like Sara Heisdorffer. She’s 24 and lives in Westminster. Like many of her friends, neither the Democratic or Republican party interest her.

“People my age will hate me for saying this,” said Heisdorffer. “But it’s kind of that special snowflake thing that millennials get crap for all the time I think.”

She says read any news story about her generation and a theme emerges.

“We’re entitled and we’re too focused on ourselves as individuals as opposed to the whole,” said Heisdorffer. “And I think that’s kind of being reflected by our political ideals and the way we choose to identify.”

Heisdorffer doesn’t feel like either party aligns with her views, which she describes as socially liberal and fiscally moderate. Like many unaffiliated voters, however, she’s not necessarily independent, she generally votes for Democrats.

It’s a long running pattern to see younger voters of any generation not identify with political parties, says Joselyn Kylee with the Pew Research Center.

“Younger people tend to be less likely to affiliate with parties than older people,” says Kylee. But, “this is as pronounced as it’s ever been.”

Millennials are shunning political parties at an even greater rate than previous generations, Kylee says political dysfunction is partly to blame.

“People give some of the most negative ratings of either party that we’ve seen in the last 20 years.”

But these trends may be changing this election. Since September, 30,535 voters have registered with the Colorado Democratic party.

That includes guys like Curtis Haverkamp, 30, who attended a Bernie Sanders rally a few months back. At the rally, he learned unaffiliated voters like him couldn’t participate in the caucus.

“So, upon hearing that I registered Democrat,” said Haverkamp.

He says he votes for Republicans as much as Democrats. But Sander’s message of income inequality really resonated with him.

“I trust him, and I think Bernie Sanders would fight the hardest to find a system that works for everybody,” he said.

Both the Sanders and Hillary Clinton campaigns have been pushing registration, so it’s not clear yet who this spike in Democratic registration will favor. But Haverkamp says either way, the day after the caucus, he’ll switch back to being unaffiliated.