WASHINGTON (AP) — The FBI was justified in opening its investigation into ties between the Trump presidential campaign and Russia and did not act with political bias, the Justice Department’s internal watchdog declared Monday, undercutting President Donald Trump’s repeated claims that he has been the target of a “witch hunt.”

The long-awaited report rejected theories and criticism spread by Trump and his supporters, though it also found “serious performance failures” up the bureau’s chain of command that Republicans are citing as evidence that Trump was targeted by an unfair investigation.

The affirmation of the investigation’s legitimacy, balanced by criticism of the way it was conducted ensured that partisan battles would persist over one of the most politically sensitive investigations in FBI history. Another review of the origins of the probe continues, and the prosecutor picked by Attorney General William Barr to lead that effort hinted Monday he’ll take a harder view of the FBI’s actions.

Monday’s review by Inspector General Michael Horowitz knocked down multiple lines of attack against the Russia investigation, finding that it was properly opened and that law enforcement leaders were not motivated by political bias. Contrary to the claims of Trump and other critics, it said that opposition research compiled by an ex-British spy named Christopher Steele had no bearing on the decision to open the investigation known as Crossfire Hurricane. And it rejected allegations that a former Trump campaign aide at the center of the probe was set up by the FBI.

It found that the FBI had an “authorized purpose” when it opened its investigation in July 2016 into whether the Trump campaign was coordinating with Russia to tip the election in his favor. The report said the FBI had cause to investigate a potential national security threat.

FBI Director Chris Wray, in an interview with The Associated Press, noted that the report did not find political bias but did find problems that are “unacceptable and unrepresentative of who we are as an institution.”

The FBI is implementing more than 40 actions aimed at fixing some of the bureau’s most fundamental operations, such as applying for surveillance warrants and interacting with confidential sources.

Those changes are in response to some of the report’s criticisms. They largely centered on how agents and prosecutors set about eavesdropping on a former Trump campaign aide who they said they feared was being targeted for Russian government recruitment.

The inspector general identified 17 “significant inaccuracies or omissions” in applications for a warrant and later renewals from the secretive Foreign Intelligence Surveillance Court to monitor the communications of former Trump campaign adviser Carter Page.

The report also details that the FBI used an informant to set up and record a September 2016 meeting with a high-level Trump campaign official. The official wasn’t identified by name, but was not a subject of the Russia investigation, the report said. While the information collected wasn’t used during the Russia probe, it does lend support to the assertions by Trump and Barr that the Trump campaign was spied upon.

The report said the errors resulted in “applications that made it appear that the information supporting probable cause was stronger than was actually the case.” The watchdog found that the FBI had overstated the significance of Steele’s past work as an informant and omitted information about one of his sources who he said “may engage in some embellishment.”

Republicans have long criticized the process since the FBI relied in part on opposition research from Steele, whose work was financed by Democrats and Hillary Clinton’s presidential campaign and that fact was not disclosed to the judges who approved the warrant.