Two Republican Senate committee chairman demanded Thursday that FBI Director Christopher Wray turn over new materials from the bureau’s bungled Russia collusion probe after newly declassified evidence raised new questions about agents’ failure to vet a key informant.

In a letter to Wray, Sen. Ron Johnson, R-Wis., the Committee on Homeland Security and Governmental Affairs chairman, and Sen. Chuck Grassley, R-Iowa, the Senate Committee on Finance chairman, expressed concerns the investigation was tainted by "Russian disinformation."

The FBI's Crossfire Hurricane investigation filed inaccurate FISA warrants while probing whether people affiliated with the Trump campaign were involved in Russian attempts to meddle in the 2016 election, according to the Department of Justice Inspector General.

Johnson and Grassley said declassified footnotes from the FBI's Inspector General showed that "the Crossfire Hurricane team’s investigative file included at least two intelligence reports stating that key parts of the reporting from Christopher Steele—reporting that 'played a central and essential role' in the decision to request FISA orders —were part of a Russian disinformation campaign."

The two senators said "the FBI knew that Russian intelligence was targeting Christopher Steele’s company, that Steele relied on sources affiliated with Russian intelligence, and at least two of Steele’s reports were described as the product of a Russian disinformation campaign."

Grassley and Johnson said that Russian disinformation in the investigation could potentially "have been widespread."

Their letter indicates that the FBI should provide the Crossfire Hurricane materials by the end of April.