(CNSNews.com) – Sen. Lindsey Graham (R-S.C.), the Judiciary Committee chairman, on Sunday promised to find out “who’s telling the truth, what actually happened,” in the days after President Trump fired FBI Director James Comey.

Graham said he will subpoena former Acting Deputy FBI Director Andrew McCabe and current Deputy Attorney General Rod Rosenstein to appear before his committee, “if that’s what it takes.”

Graham told CBS’s “Face the Nation” that “everybody in the country needs to know” if Rosenstein suggested wearing a wire into the White House to secretly record the president; and whether Rosenstein suggested invoking the 25th Amendment to remove the president from office.

Both allegations surfaced in a CBS “60 Minutes” interview with McCabe (details below).

Graham on Sunday promised to “get to the bottom of it.”

It’s stunning to me that one of the chief law enforcement officers of the land — the acting head of the FBI — would go on national television and say, oh, by the way, I remember a conversation with the deputy attorney general about trying to find if we could replace the president under the 25th Amendment.

We’re a democracy. People enforce the law, can’t take it into their own hands. And was this an attempted bureaucratic coup? I don’t know. I don’t know who’s telling the truth.

I know Rosenstein has vehemently denied it, but we’re going to get to the bottom of it. I do know there was a lot of monkey business about FISA warrants being issued against Carter Page, about dossiers coming from Russia that were unverified.

Mr. Mueller is going to look at the Trump campaign, as he should, to see if they violated any laws during the 2016 election. And I’m going to do everything I can to get to the bottom of the Department of Justice/FBI behavior toward President Trump and his campaign.

Graham said no organization, including the FBI, is “beyond scrutiny.”

“If it happened, we need to clean it up,” Graham said. “And the FBI will come out stronger. But we’ve got to get to the bottom of it. What are people to think after they watch ’60 Minutes’ when they hear this accusation by the acting deputy — acting FBI director that the deputy attorney general encouraged him to try to find ways to count votes to replace the president?

“That can’t go unaddressed,” Graham said. “And it will be addressed. That’s what oversight is all about.”

Graham noted that McCabe is trying to sell his new book, so his comments should be taken with a grain of salt.

“But he went on national television and he made an accusation that floors me. You know, I can imagine, if the shoe were on the other foot, this would — if we were talking about getting rid of President Clinton, it’d be front page news all over the world.

“Well, we’re going to find out what happened here. And the only way I know to find out is to call the people in under oath and find out, through questioning, who’s telling the truth, because the underlying accusation is beyond stunning.”

McCabe: Rosenstein raised 25th Amendment, wearing a wire

McCabe, the former acting deputy director of the FBI, told CBS News that he launched a counter-intelligence investigation into President Donald Trump immediately after Trump fired James Comey because he wondered if there was an “inappropriate relationship” or “connection” between Trump and “our most fearsome enemy, the government of Russia.”

“Are you saying that the president is in league with the Russians?” CBS’s Scott Pelley asked McCabe.

“I’m saying that the F.B.I. had reason to investigate that,” McCabe responded, adding that the existence of an investigation “doesn’t mean someone is guilty.”

McCabe said Deputy Attorney General Rod Rosenstein was “absolutely” in agreement about investigating Trump. In fact, Rosenstein’s the one who appointed Robert Mueller as special counsel.

According to McCabe, in the chaotic and stressful days following Comey’s firing, he and Rosenstein “talked about why the president had insisted on firing the director and whether or not he was thinking about the Russia investigation, and did that impact his decision.”

As part of that conversation, Rosenstein “offered to wear a wire into the White House,” McCabe said:

He said, “I never get searched when I go into the White House. I could easily wear a recording device. They wouldn’t know it was there.” Now, he was not joking. He was absolutely serious. And, in fact, he brought it up in the next meeting we had.

I never actually considered taking him up on the offer. I did discuss it with my general counsel and my leadership team back at the FBI after he brought it up the first time.

McCabe said, “The reason you would have someone wear a concealed recording device would be to collect evidence, and in this case, what was the true nature of the president’s motivation in calling for the firing of Jim Comey?”

McCabe said the FBI’s general counsel “had a heart attack” when McCabe raised the idea of Rosenstein wearing a wire into the White House: “And when he got up off the floor, he said, “I, I– That’s a bridge too far. We’re not there yet.”

McCabe also said Rosenstein raised the issue of possibly invoking the 25th Amendment to remove the president:

“I didn’t have much to contribute, to be perfectly honest, in that– conversation,” McCabe said. “So I listened to what he had to say. But, to be fair, it was an unbelievably stressful time. I can’t even describe for you how many things must have been coursing through the deputy attorney general’s mind at that point. So it was really something that he kind of threw out in a very frenzied, chaotic conversation about where we were and what we needed to do next.”

McCabe said he couldn’t confirm that Rosenstein was thinking about actually ousting the president: “But what I can say is, the deputy attorney general was definitely very concerned about the president, about his capacity, and about his intent at that point in time.”

McCabe said he didn’t “counsel” Rosenstein on the matter of the 25th Amendment. “I mean, he was discussing other Cabinet members and whether or not people would support such an idea, whether or not other Cabinet members … shared his belief that the president was — was really concerning, was concerning Rod at that time.”

McCabe said Rosenstein openly talked about which Cabinet members might vote to remove the president, but McCabe said he doesn’t remember Rosenstein saying who might vote which way.

Pelley asked McCabe what was going through his mind as he sat in a meeting at the Justice Department, talking about removing the president from office:

“How did I get here?” McCabe answered. “Confronting these confounding legal issues of such immense importance, not just to the FBI but to the entire country, it was– it was disorienting.”

Pelley read a response from the Justice Department, which called McCabe’s version of events “inaccurate and factually incorrect.”

“The Deputy Attorney General never authorized any recording that Mr. McCabe references. As the Deputy Attorney General previously has stated, based on his personal dealings with the president, there is no basis to invoke the 25th Amendment, nor was the DAG in a position to consider invoking the 25th Amendment.”

The statement also says that Rosenstein never spoke to James Comey about appointing a special counsel. The statement noted that the Justice Department inspector-general “found that Mr. McCabe did not tell the truth to federal authorities on multiple occasions, leading to his termination from the FBI.”