larrd has it right. Trump is a clear message to the current establishment that the voters think they have failed. If the GOP leaders want Trump defeated, they need to change — talk about attacking Trump on this or that issue seems like a statement from them that “We won’t change for you! We’ll just destroy any alternatives!” If they got rid of Trump, the problems would still be there. That they view Trump as the problem, not a symptom, is why they can’t defeat him.