If Bernie Sanders is the Democratic nominee for president, he’ll have to secure the votes of people like me. He won’t have a chance. A man who sings the praises of Fidel Castro’s Cuba and promises to dismantle the most productive economy on the planet won’t win over America’s moderate middle, even running against an ill-mannered, ignorant and demagogic Donald Trump.

Until 2016 I was a registered Republican. I voted for some Democrats, but mostly Republicans. In 2010 I was Oregon’s Republican nominee for U.S. Senate, challenging...