If the administration had evidence, it would be in its best interest to have shared it already. Instead they keep on pushing points they can barely articulate and that conflict with known information.

They are already backtracking on the "Cartel de los Soles" accusation, after finally realizing there's no such organization, but it was always a slang frase about corruption in the military. Maduro cannot possibly lead an organization that doesn't exist. Source: NYT.

The indictment removed almost all of the mentions of this cartel, now phrasing the accusation in much broader, vague terms.

It wouldn't surprise me if at some stage they changed tack entirely and tried a different angle than drug trafficking, since, let's face it:

It's about oil. Trump is not shy about this.