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.) said Sunday 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's probe into alleged collusion between the Trump campaign and Russia will finish unimpeded.

"Nothing's going to happen to Mueller's investigation politically. He's going to be allowed to finish it," Graham told CBS's "Face the Nation."

"I'm intent on making sure that Mueller completes his investigation without political interference," he added.

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However, Graham said he was concerned about others involved in the initial stages of the Russia probe.

"I'm very disappointed no Democrats seem to be worried about the corruption at the Department of Justice and the FBI regarding the Clinton email investigation, early stages of the Russian investigation," Graham said. "I'm worried about that."

He also expressed very little confidence that Mueller would find any evidence of collusion.

"I know that from the Judiciary point of view, we found no evidence of collusion between the Trump campaign and the Russians," Graham said. "I think [Sen.] Richard Burr Richard Mauze BurrRep. Mark Walker says he's been contacted about Liberty University vacancy Overnight Defense: Trump rejects major cut to military health care | Senate report says Trump campaign's Russia contacts posed 'grave' threat Senate report describes closer ties between 2016 Trump campaign, Russia MORE [R-N.C.] said from the Intel point of view that he's seen no evidence of collusion, but we're waiting on Mueller."

"Let's let Mueller do his job," Graham said.

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 and his Republican allies on Capitol Hill have repeatedly expressed that they want the Mueller probe to end, fueling concern among Democrats that the GOP is trying to impede the investigation.

Last Thursday, Trump told Bloomberg News that he considered the investigation "illegal," a statement the president doubled down on Sunday morning.

"The illegal Mueller Witch Hunt continues in search of a crime," Trump tweeted out. "There was never Collusion with Russia, except by the Clinton campaign, so the 17 Angry Democrats are looking at anything they can find."

"ALSO, not allowed under the LAW," he said.