So, in a murder trial;, you would call no witnesses that show your client is innocent?
So far most witnesses have agreed that Trump quid pro quo.
If the Republicans call no one, their vote is 100% political & pisses on the duty as set forth by the US Constitution.
What crime has been committed?
Witnesses who say, I presumed", "I assumed" , I heard ______ say"......that is not evidence in a court of law.
If they wanted witnesses they should have used the courts, but, they were in a hurry to a train wreck....and it did wreck for them.
Perhaps, in their next impeachment hoax with this president they will slow down.