A few comments about this:

1. Some of the signatories really surprise me.
2. Some don’t.
3. I’m not saying which are which.
4. If they had claimed, say, that “Trump will do far less damage to the American social and political order than HRC,” I’d have replied that I very much doubt that, but I can at least understand why you think so.
5. But they say “We believe that Donald Trump is the candidate most likely to restore the promise of America,” which very few of them can possibly believe.
6. I suspect then, that while they actually think that “Trump will do far less damage to the American social and political order than HRC,” they also know that saying so won’t serve to rally the troops to the Trumpian flag and produce the defeat of HRC.
7. The substance of the “Statement of Support,” then, is what Socrates in Plato’s Republic calls a “noble lie.”
8. I don’t see anything noble about it.

UPDATE: I am hearing from several sources who insist that most of the signatories here really do believe that Donald Trump — Donald. Trump — will indeed do mighty deeds that will at least help “restore the promise of America.” So I stand corrected, I guess? I certainly stand dumbfounded.