Where's the plausible deniability for Trump? 

In its attempt to warn Trump off Flynn, the DOJ clearly had something more damning than a premature phone chat with the Russian ambassador. When it said Flynn was vulnerable to blackmail, it implied there was behaviour that was blackmailable. 

Will Congress want to know what that behaviour was? Or will it be stymied by a GOP leadership not yet ready to acknowledge the emperor's abject nakedness?