Washington (CNN) President Donald Trump's lawyer Rudy Giuliani dismissed Republican Rep. Trey Gowdy's defense of the FBI's use of a confidential source to investigate potential Russian outreach to individuals connected to Trump's presidential campaign, telling CNN on Thursday, "He's drinking the Kool-Aid."

Giuliani went on to criticize Gowdy over his handling of a Republican-led investigation into the 2012 Benghazi attack, which has been criticized by Democrats as a partisan attempt to undermine Hillary Clinton. Gowdy oversaw the investigation as chairman of the House Select Committee on Benghazi.

"I never understood what he did with Benghazi either. He really screwed that up. I don't know what he was doing," Giuliani said.

Gowdy, the House Oversight Committee chairman, threw cold water on the President's suggestions that the FBI improperly spied on his campaign earlier this week when the South Carolina Republican told Fox News that he is "convinced" that the FBI acted appropriately in its handling of the investigation into Russian interference in the 2016 election and possible connections to the Trump campaign.

The President has attempted to advance claims, without offering evidence, that the FBI embedded an informant in his campaign to act as a spy. On Thursday, Trump tweeted , "The corrupt Mainstream Media is working overtime not to mention the infiltration of people, Spies (Informants), into my campaign! Surveillance much?" US officials have disputed this characterization to CNN , saying that a confidential intelligence source was not planted inside the campaign.

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