the sewer - two guys with ulterior motives. There was nothing credible produced by either of them (fyi, a "back channel" would be going through existing connections - rudy had no connections and everyone that came into contact with him realized how sketchy he was.)
LOL, I know what I'm talking about - you don't give a **** what trump did...you will rationalize away. Simply put, you have no morals.
Here's your "back channel":
https://fortune.com/2019/11/15/rudy-giuliani-ukraine-financial-dealings-feds-investigating-ukraine-scandal/