Updated

FBI officials who were involved in the Russia investigation should be "very worried" following the news that a key source for the infamous Steele dossier was under investigation over suspected contact with Russia, Sen. Lindsey Graham, R-S.C., told "Hannity" Thursday.

"It makes me mad that the FBI knew that the primary sub-source, a single individual, was a suspected Russian agent," Graham, the chairman of the Senate Judiciary Committee, told host Sean Hannity. "They used that person's work product to get a warrant against an American citizen on four different occasions. They never informed the court of this exculpatory evidence.

SOURCE OF STEELE DOSSIER WAS INVESTIGATED BY FBI FOR RUSSIAN CONTACTS, BARR SAYS

Graham added that it was important to note that Connecticut U.S. Attorney John Durham, who is leading the investigation into the origins of the Russia probe, "has already investigated this matter.

"So there's some people tonight that have to be very worried, because now we know the FBI -- in December 2016 -- knew that the dossier was being prepared by a Russian agent. They never told the court."

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Graham described the dossier as "a massive effort by Russia to do a disinformation campaign against the Trump campaign, and it worked. Bottom line, is the FBI used a document prepared by a Russian agent -- paid for by the Democratic Party -- to get a warrant against the Trump campaign, and the only place you're going to hear about that is probably on this show.

"I hope this is a game-changer," he added. "I hope that the traditional media, the mainstream media will look at this abuse of power."

Fox News' Brooke Singman contributed to this report.