Conservatives and the conservative journals of opinion are generally deeply alarmed by the Presidential candidacy of Donald Trump, and many say that under no circumstances will they endorse or back Trump in any way, fashion, or form.
This includes, among others, the following:
THE NATIONAL REVIEW
THE WEEKLY STANDARD
This is far from a complete list, but the numbers are growing daily.
They see Trump destroying the conservative movement for a generation or more, and are determined to take him down, even though they have no clear alternative to vote for.