The Gem State had an open primary system prior to 2012. When the primary election rolled around voters would just request a ballot for the party of their choice–Republican, Democrat, whatever–and then vote among the candidates on that ballot. It worked well, but not to the satisfaction of radical right-wing Republicans who wanted to tip the balance in favor of ultra-conservative candidates.
The GOP managed to close its primary to all but declared Republicans in 2012 for the sole purpose of purging more moderate, pragmatic candidates from its ranks and that is exactly what has happened. Since Idaho is one of the reddest states in the country, the winner of the Republican primary is usually the person who will prevail in the general election. Extremists just have to marshal their forces in the primary to elect those who represent their distorted views.
We need to understand that the success of their plan depended on strictly limiting the number of Idahoans who are permitted to choose who represents them in government. Idaho’s experience under the closed primary system is similar to that disclosed by the daughter-in-law of Fox News mogul, Rupert Murdoch. Kathryn Murdoch, an advocate for allowing more voters into the candidate selection process, points out that in 2020, just 10% of Americans effectively elected 83% of the U.S. House of Representatives. The newly-elected leadership of the Idaho GOP wants to further restrict the selection of public officials in Idaho to a select group of extremist Republican functionaries, excluding the great majority of Idaho voters from the process.