Sen. Lindsey Graham Lindsey Olin GrahamSenate GOP aims to confirm Trump court pick by Oct. 29: report The Hill's Campaign Report: GOP set to ask SCOTUS to limit mail-in voting Senate GOP sees early Supreme Court vote as political booster shot MORE (R-S.C.) broke with Rudy Giuliani, President Trump Donald John TrumpBiden on Trump's refusal to commit to peaceful transfer of power: 'What country are we in?' Romney: 'Unthinkable and unacceptable' to not commit to peaceful transition of power Two Louisville police officers shot amid Breonna Taylor grand jury protests MORE's personal lawyer, saying on Thursday that he's "not buying" the argument that special counsel Robert Mueller Robert (Bob) MuellerCNN's Toobin warns McCabe is in 'perilous condition' with emboldened Trump CNN anchor rips Trump over Stone while evoking Clinton-Lynch tarmac meeting The Hill's 12:30 Report: New Hampshire fallout MORE is trying to frame the president.

"Mueller's not above being scrutinized. He's not above being challenged. But I'm not going down the road of saying this is some kind of exercise to frame the president," Graham told reporters.

Graham added that he's known Giuliani for 20 years.

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"His job is to represent the president," he said. "[But] I'm not buying this."

Giuliani said at an event in Israel on Wednesday that Mueller has a group of investigators that includes “13 highly partisan Democrats ... (who) are trying very, very hard to frame him to get him in trouble when he hasn’t done anything wrong," according to The Associated Press.

Graham noted that similar arguments were made against Ken Starr, who investigated President Clinton in the '90s, and he didn't believe the arguments then, either.

Trump and his allies have repeatedly lashed out at Mueller's probe, arguing that its aim is to undermine the president.

Trump, in a tweet on Monday, declared the investigation "totally unconstitutional."

On Thursday, the president called for the Mueller team's "many conflicts of interest" to be made public.