"I think the report is going to be devastating to the President, and I know that the President's team is already working on a response to the report," Dershowitz said, after Stephanopoulos reminded him that several of Trump's former aides have cut plea deals and are cooperating with Mueller.
"When I say devastating, I mean it's going to paint a picture that's going to be politically very devastating," Dershowitz continued. "I still don't think it's going to make a criminal case, because collusion is not criminal."
Reached by phone today, as his comments pinged around the internet and raised expectations for an explosive report, Dershowitz refined them.
"What I think Mueller's going to do if he's smart is connect the open dots," Dershowitz, who has defended clients in some of the most famous cases in modern history, said.
"He's going to lay out everything that relates to contacts between anyone in the campaign and the Russians, and the same thing with obstruction of justice. None of these things by themselves are compelling, but when you lay it out and see it all in one document, I think it will be on its face very critical of the President."
That will be a bad time for Trump, assuming Mueller's report is made public, Dershowitz said. But he also expected the President to release a rebuttal, arguing that Mueller relied on noncredible witnesses and invented crimes where Trump merely exercised constitutional powers of his office.
"The rebuttal will put a different spin on it. People who support Trump will say the rebuttal seems correct," he said. "I think by 2019, we'll be back to where we are now."
Dershowitz doesn't claim to have any special access to what Mueller and Trump are doing, though he's hardly alone in expecting the investigation's end game is imminent now that Midterm elections are over.
As it happened, Trump himself opined on the matter today - not attacking the credibility of Mueller's witnesses, as Dershowitz predicts he will, but rather going after the Special Counsel himself.
"When Mueller does his final report, will he be covering all of his conflicts of interest in a preamble?" the President wrote, citing no examples.
"Will he be putting in statements from hundreds of people closely involved with my campaign who never met, saw or spoke to a Russian during this period?"