Politically, Donald is in a tricky spot. He should can Comey yesterday. But then he will be painted as one bullying Comey for political reasons, ala Nixon's Saturday night massacre.
He needs to find some incriminating evidence, show it quietly to Comey, and make him sit at his desk and be a good boy for the rest of his term or until he leaves prematurely on his own terms.
I’d prefer that Comey sit at his desk and leave office, a’la the Shawshank warden.