It is your own party killing off the moderates
With every presidential election you lose, you have missed the lesson- the GOP assumes, "well, we just didn't run with someone as ideologically pure, and right wing enough"
The actual lesson is that the GOP has alienated more and more people with its 'party of stupid' agenda- and by going further to the right they will alienate even more....
You see it happening right now... Trump may appeal to the bigots and idiots in your party (apparently a lot of them to appeal to) but overall he is hurting the GOP because most Americans find him distasteful.