This week, President Donald Trump has repeatedly attacked his Attorney General Jeff Sessions on Twitter, White House administrators have affirmed the president’s “frustration” with Sessions — and Sen. Lindsey Graham (R-SC) has had enough. “If Jeff Sessions is fired,” Graham told reporters Thursday, according to video taken by NBC News, “there will be holy hell to pay.”

Graham warned reporters on Capitol Hill: “This effort to basically marginalize and humiliate the attorney general is not going over well in the Senate. I don't think it's going over well in the conservative world. If you believe Jeff Sessions should be fired, use the power you have and accept the consequences. I hope it stops. I'm 100 percent behind Jeff Sessions.”

“Any effort to go after Mueller could be the beginning of the end of the Trump presidency, unless Mueller did something wrong,” Graham added.

The public feud between Trump and Sessions has, at its heart, Trump’s desire to clamp down on the investigation into potential ties between Russia and the Trump campaign, which is being led by special counsel Robert Mueller. Attorney General Jeff Sessions advised Trump’s campaign and, because of that, recused himself from the investigation in March.

That prompted Trump’s frustration and the president’s recent admission to New York Times reporters that he wouldn’t have chosen Sessions as attorney general if he knew Sessions would recuse himself from the investigation. It now appears to many that Trump is trying to push Sessions out of his position at the top of the Justice Department.

On Wednesday, Graham told CNN’s Manu Raju that Trump is showing weakness by threatening Sessions on Twitter and not just using the power he has to fire him. “He is trying to get Sessions to quit, and I hope Sessions doesn’t quit. If the president wants to fire him, fire him!” Graham said.

On Thursday, Graham expressed increasing concern about rumors that Trump is planning on firing Sessions.

WATCH: Sen. Lindsey Graham says there will be "holy hell to pay" if AG Jeff Sessions is fired.



Video via @VaughnHillyard pic.twitter.com/g4gqmzqOyl — NBC News (@NBCNews) July 27, 2017

Here are Graham’s full remarks from Thursday:

As a human being, I think he should show respect for Jeff Sessions as a person. Jeff Sessions was the most loyal supporter of Donald Trump. A rock-solid conservative. The reason I like him so much is I often disagree with him, but I'd never believe he was a man who lacks integrity or fair play. This effort to basically marginalize and humiliate the attorney general is not going over well in the Senate. I don't think it's going over well in the conservative world. If you believe Jeff Sessions should be fired, use the power you have and accept the consequences. I hope it stops. I'm 100 percent behind Jeff Sessions. The chairman of the Judiciary Committee sent a pretty chilling tweet yesterday. There will be no confirmation for a new attorney general in 2017. If Jeff Sessions is fired, there will be holy hell to pay. Any effort to go after Mueller could be the beginning of the end of the Trump presidency, unless Mueller did something wrong.

Graham also told reporters that he is working on legislation that would prevent the firing of special counsels without judicial review, according to NBC.