It's not just Trump who is blowing it, it's House Republicans. They made the mistake of calling FBI director James Comey to testify today, as a way to milk as much as they can out of the email investigation. 

Comey is undermining all of the GOP talking points.  " know no reasonable prosecutor would bring this case," Comey said.  

He also said that he does not believe that General David Petraeus "got in trouble for less," a reference to a tweet by Donald Trump. "Petraeus willingly leaked classified information and then lied about it and that his actions were intentional."