Sen. Lindsey Graham on Tuesday said it would "probably" be an impeachable offense if President Donald Trump fired special counsel Robert Mueller without cause.
In an interview with conservative radio host Hugh Hewitt, Graham, R-SC, said he empathizes with Trump's frustration with the Justice Department for being "overly political," but said that can't justify firing Mueller.
"I think what the president will have done is stopped an investigation (into) whether or not his campaign colluded with the Russians, what effect the Russians had on the 2016 campaign," Graham told Hewitt. "I can't see it being anything other than a corrupt purpose.
"I've seen no evidence of collusion, but to stop an investigation without cause, I think, would be a constitutional crisis," Graham said.
Hewitt asked Graham if he had conveyed to the president to not fire Mueller.
"I think I just did," said Graham, who earlier this week said firing Mueller would be the "beginning of the end" to Trump's presidency.
But Graham understands the president's frustration.
"The FBI's handling of the dossier was really unprofessional, inappropriate. The Clinton email investigation was a joke. McCabe probably deserves to be fired," Graham told Hewitt.
"So the president's right to be upset with the Department of Justice being overly political. He would be wrong, in my view, to try to stop this investigation without cause on the Mueller side. They're disconnected in time. Mueller came along long after this. He's looking at things unrelated to the dossier," Graham told Hewitt.
However, Graham does believe a second special counsel should be impaneled to address the missteps of the Justice Department and the FBI.
The DOJ "can't grade their own homework. Somebody outside the system needs to take a fresh look," Graham said. "You need a second counsel to look at how the FBI agents behaved when it came to the Clinton email scandal."