So, you want to take away the first Amendment rights of pasters and Christian leaders. Leaders from all other walks of life endorse and I see no reason why Christian leaders should not do so as well. Honestly, for all of Trump’s supposed political correctness some of his supporters sound like card carrying members of Americans United for the Separation of Church and State.
They can do what they want as Americans.
Just don’t take it and try to guilt and shame people as somehow being against God and Christ if you disagree with their endorsement.
They should make their endorsements as Americans, not as the person between you and God, which is how it is wielded.