(I know you edited I just want to address this)i think the issue is whether he threatened to withhold funding from ukraine which did not happen (in this transcript)
Saying it needed to be an explicit quid pro quo (or extortion to be more accurate) is pushing the goalposts into more favorable territory for the Republicans.
A sitting president blatantly asking a foreign head of state to investigate into his political rivals as a "favor" is still highly inappropriate and impeachable.