When Mitt Romney announced his intended retirement from the U.S. Senate on Sept. 13, 2023, the Atlantic published an excerpt from his upcoming biography, in which the 2012 Republican presidential nominee told author McKay Coppins, “A very large portion of my party really doesn’t believe in the Constitution.” This claim would have been startling 15 years ago. For decades, the Republican Party has been the party of conservatism and a champion for the Constitution. Romney is clear that Donald Trump, who leads what he calls a “populist” and “demagogic” portion of the party, is to blame. And Romney is not...