Last fall, Matt Edwards, a conservative activist from Hayden, sent all 105 Idaho legislators a pledge. By signing the statement, lawmakers would promise to support what he termed medical freedom and privacy, election integrity and education freedom. They would also vow not to raise taxes, suppress free speech or support government lockdowns. “Only four Idaho senators signed the pledge. Since then, Edwards’ political action committee, Citizens Alliance of Idaho, with help from other deep-pocketed right-wing reformers, has spent nearly $200,000 to promote incumbent senators’ primary election opponents. The pledge is emblematic of a larger rift in the Idaho GOP over...