Agree.  Trump's Tweet threat for Comey to keep quiet smacks of desperation, because if Comey testifies under oath in Congress that Trump told him to 'pledge loyalty' and squash the Russian investigation, BOTH Republican and Democratic Congressman will have no choice but to start an independent investigation, similar to what was done with Nixon and Watergate.  It would be ironic that Trump tapes his conversations like Nixon and they become evidence in the investigation that latter is made public.  Bet some of the conversations are revealing as Trump wanting Tic Tacs for his breath or grabbing a woman be her poo say.  His Comey Tweet threat might actually be a self fulfilling prophecy of Trump actually getting impeached and himself getting fired as President of the United States.