Donald Trump supporters are angry that all 34 of Colorado’s delegates went to Republican presidential hopeful Sen. Ted Cruz (R-TX). And they’re taking it out on the state’s GOP chairman.

Colorado GOP Chairman Steve House started receiving death threats from Trump supporters on Sunday, according to a local Denver ABC News affiliate.

Angry voters are complaining that the state’s multi-step system of caucuses — which allows party activists to select the state’s presidential nominating delegates that will represent them at the national convention in Cleveland this summer — unfairly shut out Trump. The Republican frontrunner himself has also argued the system was a “crooked deal” and that millions of his supporters weren’t able to have their voices heard. Other states hold primaries and caucuses that give voters the opportunity to decide who they want on as their party’s nominee.

House’s telephone number was made public on the internet and, over the past several days, he has received more than 2,000 calls from people complaining about the process — including some that have threatened the safety of his family.

“Do me a favor,” read one of the threats sent to House. “Get your gun, put it in your mouth, pull the trigger, I’ll call you back in two minutes. If you can’t do that, I’m gonna send somebody over to the house and help you.”

“Shame on the people who think somehow that it is right to threaten me and my family over not liking the outcome of an election,” House wrote on Facebook, according to the Hill.

The New York Times reported that the anger came as a surprise to some Colorado Republicans, given that the party “decided last August to do away with its presidential straw poll. After the Republican National Committee decided that the outcome of state straw polls would have to result in bound delegates, the state party decided that it would be too risky to use that kind of system because of potential problems counting that many ballots without state resources.”

“Not understanding that is one thing, but it’s hardly rigged when it’s done right out in the open,” Republican National Committee (RNC) spokesperson Sean Spicer said, according to Reuters.

RNC Chair Reince Priebus also agreed, taking to social media to say that it was up to Trump’s campaign to accept the nomination process that had been agreed to last August.

Death threats aren’t isolated just to GOP officials in Colorado. Tom John, the Indiana GOP’s 7th District Committee Chairman received an eerie warning after he told Politico that Trump “doesn’t represent what I want my party to represent.” That anonymous email stated that John was being watched. And Trump ally Roger Stone once threatened to send supporters to delegates’ hotel rooms if they switched from Trump to another candidate.

These threats follow a string of violent incidents around the country against other delegates and people who don’t support Trump.

There’s a well-documented history of Trump supporters going on verbal tirades and committing violent assaults against people who don’t agree with them. Trump, who built his campaign on disparaging immigrants, Muslims, women, and people of color, has yet to disavow the actions of his supporters. Instead, he has praised them for being “passionate.” ThinkProgress has tracked the locations where violent protests involving Trump’s supporters have broken out.

Some research has even suggested that Trump’s rhetoric is making children mean, encouraging them to bully their immigrant, Muslim, and refugee classmates.

For his part, Trump has continued to tweet about the perceived injustice in Colorado where he claimed that “one million people have been precluded from voting.”

A “peaceful protest” by Colorado Votes Matter, a grassroots collective of state voters who supports Trump, has been planned for Friday at the State Capitol.