Washington Post obtained excerpts of the review in which Justice Department's inspector general is expected to critique James Comey's actions while he headed the FBI's investigation into Hillary Clinton's email scandal.
The inspector general also released a report in April finding that Deputy FBI Director Andrew McCabe lacked candor on four different occasions regarding interactions with the media, including providing information to a news reporter about the FBI's investigation into the foundation created by Hillary and Bill Clinton.
The report by Horowitz on the FBI's handling of a probe into Clinton's emails is due to be released publicly at 2 p.m. (1800 GMT). "Hope Report is not being changed and made weaker!" Clinton herself has blamed Comey in part for her election loss to Mr. Trump. Horowitz will give the report to Congress on Thursday, and it's likely to have a big fallout. There are so many awful things to tell, the public has the right to know.
Horowitz' report had criticism for Peter Strzok and Lisa Page as well, but also did not find evidence that the political bias expressed in their texts to each other impacted their investigation.More news: Sarah Huckabee Sanders leaving White House, reports claim; Sanders responds
The report did hammer Comey's handling of the Clinton investigation, but did not assert any political "bias".
The report was welcomed both by Democrats, who thought Comey's reopening of Clinton's email server investigation just days before the election cost her the race, and by Republicans, who felt Clinton deserved criminal charges for using a private server to send emails related to her work as Secretary of State.
Watch the full report above.
However, Trump's original justification for axing Comey - failing to follow Justice Department protocols - quickly fell by the wayside when Trump said he did it with the "Russia thing" on this mind.More news: NY attorney general sues Trump Foundation, alleges illegal self-dealing
In another tweet, the Democratic senator wrote: "I'm calling it now: no matter what the DOJ IG report actually says, President Trump's sycophantic supporters will try to claim that somehow he is the victim of Federal Bureau of Investigation wrongdoing & bias".
The president again denounced the investigation into his campaign in a Thursday morning tweet. "Right?!" Page wrote to Strzok.
Strzok and Page would later be removed from the investigation over the text messages, which were obtained by internal investigators.
In an interview with the Hill's new television show "Rising", which aired Thursday, Attorney General Jeff Sessions said he is open to firing employees if the inspector general's report warrants it.More news: Pompeo: Trump North Korea tweet was done with 'eyes wide open'
Comey has claimed in testimony before Congress that he cut Lynch out of the loop because he considered her compromised in relation to the Clinton probe.