I am a bit amused by the claim Sen Risch made that Mr Trump did not order xDir Comey to end investigation, because Mr Trump did not use the words "I order you ...".
If Mr Trump wanted to order someone to do something he could just issue a memo. If he however wanted a favor from xDir Comey, he would have hoped xDir Commey could end the investigation.
Can the President ask a favor without it being an order?