The message to Mueller could not be clearer: What do you got? And it is asked with a New York swagger that perhaps only Rudy has perfected more completely than Trump. Giuliani is convinced that the Mueller investigation has nothing on his client. It may indict Russians, it may find that Paul Manafort engaged in shady business practices, it might find that James Comey bravely broke the law, but on Trump it has nothing.
That’s the bet. It’s the marker Rudy is laying down. He says Mueller has bubkis, and he’s offering the special counsel a way out, offering an off-ramp to a constitutional crisis. Mueller can seek a subpoena and compel the president to testify under oath with no constraints. He might win; he might lose. But if he has evidence of collusion, why not take the offered opportunity to confront Trump about that evidence? Why not take the offer Giuliani is giving?