It is unclear if Trump understands the implications of mentioning the “made-up Russia story” in the same sentence that he discussed his reasons for firing Comey. If Trump were to admit that he fired Comey because he was irked by the FBI’s investigation into the Trump campaign’s possible connections to Russian election interference, he would be admitting to obstruction of justice.
That same charge was what ultimately led to President Richard Nixon’s resignation. Nixon was investigated for obstruction of justice for his hand in covering up the break-in at the Watergate Hotel. With this latest gaffe, the parallels between the two presidents have become more glaring.
First, if what has been "reported" by such venerable news organizations as the WaPo or NYT can be relied upon, the investigation was begun because of an unreliable dossier that was prepared for opposition research. No intelligence agency ANYWHERE has found it credible, so IF as has been reported and that is true, Trump is correct in being "irked" and questioning the already questionable judgment of Comey. Plus, the firing of Comey doesn't impede or obstruct the investigation, as was testified under oath by Acting FBI Director (and Democrat) McCabe. Also, Grassley AND FEINSTEIN that Comey did inform them that the President is NOT under investigation. So, as was laid out by Rosenstein, there was just cause to fire Comey, and even if he was investigating Trump, Trump could still fire him for his mishandling and job performance elsewhere. Otherwise, every FBI agent would undertake investigations of every president the moment the election is over for job security. That is a ridiculous notion!
Second, as has been pointed out by many legal experts, firing an FBI Director is COMPLETELY different from firing the AG, the Dep. AG and a Special Prosecutor. Any attempts to link them are not born by reason or logic.