My most difficult writing assignment

My friend Pat would like to put messages on cars with Trump bumper stickers explaining how Trump is destroying American values and the American political system.  She would like the message to be reasonable and delivered in such a way that the recipients are not insulted, but instead begin to understand why Trump is such a disaster.  She is hoping to convert rather than condemn.

She asked me to write it.  She said I was a good writer, and she is depending on me to draft the message.  

I’ve had difficult assignments in the past, but this one is really really hard.  I sit at my keyboard, write something, delete it, write something else, delete it, and so it goes.  I just can’t come up with the right words.  I’m beginning to think I might not be able to do this.