Republican Sen. Lindsey Graham wants former FBI Director James Comey to testify again to Congress after new details emerged last week about the Hillary Clinton email case.

"This doesn't add up, and I smell a rat here," Graham told Fox News on Thursday.

Graham and Sen. Chuck Grassley, the chairman of the Senate Judiciary Committee, wrote last week in a letter to the FBI that Comey started to draft a statement exonerating Clinton in the bureau's investigation into her use of a private email server before the FBI interviewed her or her key witnesses.

The Judiciary Committee reviewed transcripts that indicated Comey began writing the exoneration statement in April or May 2016.

Comey announced in July 2016 that FBI would not recommend criminal charges against Clinton.

"He needs to come back to the committee," Graham said.

Graham said he wants to know whether Comey had "predetermined the result" of the Clinton investigation before she and her aides were interviewed, "contrary" to his testimony.

Graham told Fox News he has reason to believe the "real reason may have been some email between the DNC and the Justice Department about the scope of the Clinton investigation."