Sen. Lindsey Graham, R-S.C., on Monday slammed the FBI's investigation into President Trump’s 2016 campaign as a “criminal enterprise” that got off the rails.

Graham delivered his remarks during a news conference in which he reacted to the long-awaited review concerning the origins of the Trump-Russia probe.

“Let’s assume for a moment it started out okay. It sure as he-- didn’t end okay,” Graham said referring to investigators' efforts to seek a Foreign Intelligence Surveillance Act (FISA) warrant to monitor former Trump campaign adviser Carter Page in the early months of the Russia investigation.

“I believe there will be no debate among reasonably minded people, particularly lawyers, about how the system got off the rails, but in my view became a criminal enterprise to defraud the FISA court, to deny American citizen Carter Page his constitutional rights, and to continue an operation against President Trump as president of the United States,” he said.

Sen. Chuck Schumer, D-N.Y., giving his take on the FISA report during an earlier news conference, said the report put to rest any notion that the FBI’s investigation of Trump’s 2016 campaign was politically motivated.

“This report conclusively debunks the baseless conspiracy that the investigation into Mr. Trump’s campaign and its ties to Russia originated with political bias.”

Schumer again reiterated that the FBI investigation was “valid and without political bias.”

Anticipating that his Republican colleagues will do their “level best to reject the report’s conclusions,” Schumer pointed out that FBI Director Christopher Wray – a Trump appointee – has “already embraced the central findings.”

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He quoted Wray as saying he did not believe the FBI unfairly targeted the Trump campaign.

Schumer also said it was “ironic” that officials including Attorney General William Barr and Graham, who have praised Horowitz in the past, later questioned the report.

“Because the IG issued a report whose conclusions he doesn’t like, Senator Graham ought not to question what he upheld last week,” Schumer said.

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The report listed multiple errors by the FBI in its efforts to obtain a FISA warrant. The IG probe identified at least 17 “significant inaccuracies and omissions” in the Page applications and said a new audit into the FISA process would take place.

Horowitz and his investigators were at times critical of the bureau’s handling of the cast, including for failing to share information that would have undercut claims in those warrants.

Fox News' Ronn Blitzer and Brooke Singman contributed to this report.