In 2014, the Utah legislature passed a bill providing that a candidate can get on a primary ballot even if he or she does not have much support at a party caucus. Prior the the 2014 bill’s passage, Utah was the only state in which it was impossible for anyone to get on a partisan primary ballot for any office unless the candidate showed prior support at a party caucus.
The Utah Republican Party doesn’t like the 2014 bill, and will soon file a lawsuit to overturn it, according to this story.
The U.S. Supreme Court decision New York State Board of Elections v Lopez Torres, issued in 2008, makes it likely that the proposed lawsuit will win. That decision, which was unanimous, affirmed that political parties have a First Amendment right to stop direct nomination of candidates in their own primaries, if that is what they want. The 2008 decision upheld a New York law that says political parties nominate candidates for Supreme Court Justice in party conventions. The lower courts had said there must be a method for candidates to get on a primary directly, but the U.S. Supreme Court reversed the lower courts.