(CNN) Former FBI Director James Comey drafted a statement exonerating former Secretary of State Hillary Clinton for running her government emails through a private email server before completing the investigation, according to two Republican senators.

Comey prepared the draft exoneration for Clinton before conducting interviews with top Clinton aides who were offered immunity for their cooperation, Senate Judiciary Chairman Chuck Grassley and Sen. Lindsey Graham said Thursday in a joint statement, citing transcripts of interviews with former Comey aides obtained by the Senate judiciary committee.

Comey would go on to announce in July 2016 that the FBI would not recommend charges against Clinton -- although he sharply chastised her decision to conduct State Department business through a private email server.

"Conclusion first, fact-gathering second -- that's no way to run an investigation. The FBI should be held to a higher standard than that, especially in a matter of such great public interest and controversy," Grassley and Graham wrote in a letter to FBI Director Christopher Wray seeking more information -- including all drafts of Comey's final statement on Clinton's emails by September 13.

None of the committee's Democrats signed onto the request.

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