[Blumenthal said the president had pre-empted an inspector general investigation of Comey's actions by firing him with "a pretense that is laughable."]
Just a quick run through the evidence.
The explanation for firing Comey was that he handled the Clinton email investigation.  If this is true why didn't he fire Comey three months ago?  Because the DOJ was investigating the issue?  The DOJ is still investigating the issue so why didn't Trump wait for the investigation's conclusion before firing Comey?
And as usual Trump passed the buck whenever there is a contentious issue involved.  In this case he only "acted" on the advice of the AG (who had to recuse himself from the Russian investigation) and the deputy AG (who just moved into the position a couple of weeks ago).
Then we get to add this with recent activity over the last few weeks.  The request for increased resources, the refusal to play ball and support the wiretapping claim and the refusal to say Trump wasn't under investigation