So what would work?
Reason? Tried it. Hasn't worked.
Pointing out Trump's conflicting positions in his own words? Tried it. Hasn't worked.
Pointing to Trump supporters own past statements, longing for a true conservative candidate for president? Tried it. Hasn't worked.
If all else fails, and Trump supporters put on their blinders to keep from being swayed from their cult of personality, you may as well just call a spade a spade and not worry about the resulting butt-hurt.
That dumb bastard candidate of yours is not ENTITLED to our votes.
If you can’t get the support then go F off and work with what you have.