Bias may have crept into the process by which the FBI sought the authority to monitor electronically a onetime member of President Trump's campaign, according to Justice Department Inspector General Michael Horowitz.

An assessment from the DOJ watchdog found the Trump-Russia investigation was opened on a sound legal footing and was unable to "find documentary or testimonial evidence that political bias or improper motivation influenced" the genesis of that investigation.

But Horowitz, who released a report on Monday regarding the FBI's counterintelligence investigation into the Trump team, distinguished between the opening of the inquiry in late July 2016 and the investigatory actions related to the Foreign Intelligence Surveillance Act that followed.

“We asked all the witnesses — not just him — as to whether bias or other improper considerations had any impact, but we also looked for emails, text messages, documents that could show what we found, frankly, with Strzok and Page,” Horowitz said while answering a line of questioning by Idaho Republican Sen. Mike Crapo during a Senate Judiciary Committee hearing on Wednesday.

Horowitz was referring to Peter Strzok and Lisa Page, former FBI officials who were part of the Russia investigation before being removed due to the discovery of anti-Trump text messages that the inspector general found in a prior investigation. One revelation in Horowitz's latest report is that Strzok was involved in the decision to initiate the counterintelligence investigation, but it was his superior, Bill Priestap, the assistant director of the FBI Counterintelligence Division, who made the actual authorization.

Horowitz agreed with Crapo's statement that “in this case, what you’re saying is you could not find any documentary or testimonial evidence to contradict the statements of the investigators that they were not letting bias influence their decision.”

Stressing that he could "only speak to the evidence we found," Horowitz said, “I think the important point here, and I made earlier, all the evidence is here. People are free to consider, evaluate what they think ultimately people’s motivations were."

“We’re not making a decision on ultimately information or evidence we don’t have that somebody may have acted,” Horowitz added.

According to Crapo, GOP senators “think there’s tons of evidence of bias here." He asked, “You have referred for further action to the attorney general, one case for criminal prosecution, if I understand it right, and other cases of how many other individuals?”

“I want to be clear — now we’re talking about the FISA as opposed to the open,” Horowitz said. “There’s a very significant distinction. And I’ve tried to separate those.” The inspector general said his findings on possible FISA abuse had been sent to the attorney general and the bureau “for adjudication and consideration.”

Crapo noted that leaves open the question of what the FBI or attorney general could find with these referrals.

“There are significant serious failures here on the operation — particularly in connection with FISAs,” Horowitz said. “Whether it was sheer gross incompetence that led to this versus intentional misconduct or anything in between and what the motivations are, I can’t tell you as I sit here today. I don’t have enough evidence to reach a conclusion.”

Crapo asked, “If someone were to characterize what you’re telling us to be that you’re telling us there’s ‘no bias’ here, that’s not what you’re telling us?”

“That is not, as to the operation of these FISAs, what I’m telling you,” Horowitz said.

More than a year and a half after opening an investigation following Republican allegations of surveillance abuse in the targeting of Carter Page, a former foreign policy adviser to the Trump campaign who was suspected of being a Russian agent, the inspector general found the bureau made "at least 17 significant errors or omissions" in the FISA applications spanning from October 2016 to summer 2017. Page, an American who denied being a Russian asset, was never charged with a crime.

Crapo said it was “mind-numbing” to think that all the missteps “could be just accidental.”

“I would be skeptical, but I understand why people would be skeptical of that," Horowitz said, adding that “there is such a range of conduct here that is inexplicable.”

The watchdog said, “The answers we got were not satisfactory that we’re left trying to understand how could all these errors have occurred over a nine-month period or so among three teams, hand-picked, one of the highest profile if not the most high-profile case of the FBI going to the very top of the organization and involving a presidential campaign.”