Maybe those states had/have old right isolationist tendencies that made anti-war/anti-draft/civil libertarian candidates appeal to them?
Frank Church's Idaho was the home of Sen. William Borah (R-ID) who was one of the bitter end Republicans who opposed ratification of the Treaty of Versailles at all costs.
William Borah was one of the greatest Senators in American history.
The man was a Nazi sympathizer who was delusional enough to believe he could talk Hitler out of war. His and his fellow “Irreconilable” Republicans’ refusal to ratify the Versailles treaty also arguably helped lead to WW2, as the US being in the League of Nations might have actually made a difference. Even if it still happened, the US being involved earlier could have saved millions of lives.
