Donald Trump supporters are incensed after his rival Ted Cruz won Colorado this week in a series of district conventions followed by a state convention on Saturday. Some went so far as to threaten to vote for a Democratic candidate in the general election.

Their issue is rooted in their belief that Colorado’s complicated process of choosing delegates is “politically corrupt,” “unfair” and “undemocratic.” Unlike most other states, Colorado voters select county-level delegates who, in turn, elect the delegates attending the Republican National Convention, where the GOP nominee for president is selected. (The only other state with a similar system is North Dakota.)

In their criticisms of the process, Trump supporters echoed what Trump’s campaign has reportedly also said: that Colorado’s system inherently benefited Ted Cruz, since he’s developed a strong network of supporters in the state including Republican activists and lawmakers.

More Ted Cruz Shuts Out Donald Trump In Colorado

Anger among Trump supporters was fueled by a tweet posted on the Colorado GOP’s Twitter account: “We did it. #NeverTrump,” a tweet on Saturday evening said, after Cruz won all the delegates up for grabs in the state this week. While the Colorado GOP later said the post was “the result of unauthorized access to our account and in no way represents the opinion of the party,” Trump fans were quick to hurl anger at the GOP and decry Colorado’s system.

On social media, some fiercely attacked the Republican party as corrupt, while others voiced hope that this year’s election can give rise to a third party option, so they won’t have to align themselves with either the Republican or Democratic parties. “We will have a 3 party system before long,” one user on the /r/the_donald subreddit wrote.

Another grimly stated it “feels like democracy is dead, it’s about time to revolt and demand an end to this shady backroom bullshit.”

Comments on the Colorado GOP’s Facebook reflected the same sentiment. One user, John Henrickson, slammed Colorado’s “arcane” rules and procedures.

Others said they would no longer support the GOP given the results in Colorado.

And some primarily took issue with the tweet on the Colorado GOP account declaring “We did it. #NeverTrump.”