Looks like some Democrats in Lauren Boebert's district may have taken matters into their own hands, trying to knock her out in the Republican primary. Via CPR News:

Thousands of voters have recently left the Democratic Party in Western Colorado — some as part of a grassroots effort to defeat Republican Congresswoman Lauren Boebert in her upcoming primary election.

Among them is Steven Hallenborg of Montrose.

“Well, I'm a lifelong Democrat, and now I'm unaffiliated,” he said. Because he changed his affiliation, he now can vote against Boebert in the June 28 Republican primary.

For the last few years, Colorado’s “open primary” system has allowed unaffiliated voters to participate in either party’s primary elections. That means voters like Hallenborg can weigh in on Boebert’s primary run — without actually joining the Republican Party.

The mass migration only seems to be happening in Boebert's district, where 3,600 Democrats switched their registration to unaffiliated. No other Colorado district has seen a comparable change over the last few months; neither party has lost more than a few hundred voters in other areas.