I’d characterize the conversation as suggestive, but obviously not a smoking gun. There’s nothing here that directly indicates aid is going to be withheld, but certainly nothing that’s inconsistent with it, either.
It’s not a problem for Trump to ask Zelensky to go back and look at the role of Ukrainian actors in 2016; this is simply asking a foreign leader to cooperate in a probe that has been being undertaken by the United States Department of Justice. Hence, one assumes, the references to Attorney General Bill Barr.
Asking for an investigation of a political opponent is obviously more troubling. But this is a little fuzzy, since it isn’t clear whether Trump is asking for an investigation of Biden forcing the firing of the prosecutor in question, or asking for an investigation into Hunter Biden, or both. Zelensky says in response to this request from Trump that he’s getting a new, better prosecutor and also says the new prosecutor will look into the situation, “specifically to the company you mentioned” (although this account of the conversation doesn’t record Trump specifically mentioning the energy company that had Hunter Biden on the board).
Trump repeatedly mentions that Attorney General Barr and Rudy Giuliani will follow up. We know from the Justice Department that Barr never did, but obviously Rudy was knee-deep in this matter. All roads lead to him in terms of what happened subsequent to the call.
Finally, I think the transcript clearly opens up an avenue of defense, which is that Trump only wanted to know about Ukrainian meddling in the 2016 election and about the propriety of Biden’s pressure campaign against the Ukrainian prosecutor, where the vice president had at least an appearance of impropriety.
Usual caveat: We don’t know what we don’t know, and we will soon learn more.