Mr Trump's comments on Twitter represented his first public statements on the report released on Thursday by the department's inspector general, which was critical of several key Federal Bureau of Investigation figures in the Hillary Clinton email probe.
The President on Friday took issue with the report's conclusion. "And I think that the Mueller investigation has been totally discredited". There was no obstruction.
The messages between FBI agent Peter Strzok and FBI lawyer Lisa Page - both of whom worked on special counsel Robert Mueller's Russia probe - have also given congressional Republicans ample fodder to criticize the Clinton investigation, which eventually cleared her, and to question the department's ongoing probe into Russian intervention and whether President Donald Trump's Republican campaign was involved.
Horowitz's report, released Thursday, singled out then-FBI Director James Comey for harsh criticism and referred five other bureau employees for potential disciplinary action.
Two Republican-led House committees say their own monthslong probe into the now-closed FBI investigation of Hillary Clinton's emails has so far shown "questionable decision-making" by the agency.
New York's attorney general wants to shut Trump's charity down with a new lawsuit filed Thursday that says the Trump Foundation pushed Trump's self-interests and boosted his presidential bid.
Speaking recently to reporters, Trump suggested the inspector general's findings could be something of a "birthday present" for him. Right?!" Another senior employee responds: "No. "It's like, we'll stop him with the power of the vote?"
And then, just days before the election, Comey went public again, to tell lawmakers he had found no new bombshells and would again close the investigation with no charges - on November 6.More news: Brazil held to a 1-1 draw by Switzerland
Trump can use that to vindicate his firing of Comey - and he is. He added: "What he did was so bad in terms of our Constitution, in terms of the well-being of our country".
The records of the messages were published in a report from the Department of Justice's inspector general, which conducted an internal review of the FBI's handling of the inquiry into the Clinton email investigation.
It is apparent though that he is building a possible case against Trump for illegally trying to impede the investigation.
TRUMP: "I mean there was total bias".
The IG report did not look into the Trump campaign's activities and is completely separate from the Mueller Russia probe.
FBI Director Christoper Wray said "nothing" in the report "impugns" the integrity of the FBI workforce and that while the report found "errors in judgment" and policy violations, it found no evidence of political bias or improper consideration "actually impacting the investigations under review".
The House is now controlled by Republicans but Democrats have a chance to seize control in November, which would leave Trump vulnerable. But the special counsel is a Republican and some others on his team owe their jobs largely to Republican presidents.
So while the Comey letter reminded voters of the recklessness of Democratic Party candidate, it was neither an act of bravery nor partisan sabotage to send it. That makes it three strikes at Justice, as Wray joins Attorney General Jeff Sessions and deputy AG Rod Rosenstein as Trump's biggest whiffs. Strzok, who had helped lead the Clinton probe, was removed from the Russian Federation investigation by special counsel Robert Mueller after the texts came to his attention.