Ted Cruz’s big win in Wisconsin Tuesday was an important moment for the Never Trump forces that hope to keep Donald Trump from amassing the delegates he needs to win the Republican nomination outright. But Mr. Cruz’s supporters remain seriously frustrated anyway, to the point where they have begun denigrating and demonizing Mr. Trump’s supporters, a tactic that can do neither Mr. Cruz nor his party any good.

Wisconsin was a big Midwestern contest that provided Mr. Cruz with the opportunity to show he can appeal to a broader constituency than just the hard-line and evangelical conservatives who have been his main strength.

But the results showed that many supporters in Mr. Trump’s most steadfast constituency, non-college-educated whites, stuck by him. Exit polls show that Mr. Cruz won 48 percent of this group, but more than one-third of them still voted for Mr. Trump. This confounding fealty is maddening to some Never Trumpers, who have turned their anger on the people who have stayed loyal to Mr. Trump.

Erick Erickson, a conservative commentator, calls Trump supporters “Branch Trumpidians,” and appears to spend much of his time retweeting insults of them. Last week Mr. Erickson wrote that the only people who love Mr. Trump “are white supremacists, neo-Nazis, a white victim class of mostly blue-collar workers, a group of white folks who have failed at life and blame everyone else for their own bad decisions.”