Sen. Lindsey Graham: Trump firing Robert Mueller 'probably' would be impeachable offense

Jessica Estepa | USA TODAY

Show Caption Hide Caption Trump goes after Mueller as GOP plans next steps The White House insists President Trump is not planning on firing special counsel Robert Mueller. Still, some Republicans are alarmed that about the possibility and warning that Mueller's investigation should be allowed to play out unimpeded. (March 19)

Sen. Lindsey Graham, a frequent critic of President Trump, said Tuesday that firing special counsel Robert Mueller would likely lead to a constitutional crisis and be an impeachable offense.

Graham said while he has seen no evidence that there had been collusion between Trump and the Russians, he did not think Trump could stop Mueller’s probe without cause, the South Carolina Republican explained on the Hugh Hewitt Show.

"Well, I think what the president will have done is stopped an investigation in whether or not his campaign colluded with the Russians, what effect the Russians had on the 2016 campaign," Graham said. "I can’t see it being anything other than a corrupt purpose."

Sen. Jeff Flake, R-Ariz., also raised the prospect of impeachment if Trump fires Mueller without cause.

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"We are begging the president not to fire the special counsel. Don't create a constitutional crisis," Flake, a retiring one-term Arizona Republican, said in a Twitter message Tuesday. "Congress cannot preempt such a firing. Our only constitutional remedy is after the fact, through impeachment. No one wants that outcome. Mr. President, please don't go there."

We are begging the president not to fire the special counsel. Don't create a constitutional crisis. Congress cannot preempt such a firing. Our only constitutional remedy is after the fact, through impeachment. No one wants that outcome. Mr. President, please don't go there. — Jeff Flake (@JeffFlake) March 20, 2018

The tweet using the "I" word — impeachment — marked an escalation in Flake's rhetoric about Trump; on Sunday, Flake warned that firing Mueller was "a massive red line that can't be crossed."

Graham, who was one of the impeachment managers in the House when it voted to impeach Bill Clinton, said impeachment was a check and balance on the presidency.

"I can’t think of a more upsetting moment in the rule of law to have an investigator looking at a president’s campaign as to whether or not they colluded with a foreign government, what kind of crimes may have been committed," he said. "I’ve seen no evidence of collusion, but to stop investigation without cause, I think, would be a Constitutional crisis."

The senator said the president was right to be upset over the politicization of the Justice Department and the FBI, especially in the agencies' handling of the investigations into both the unsubstantiated dossier about Trump and Hillary Clinton's emails.

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But that was no excuse for actually ending the investigation, Graham said.

"They’re disconnected in time. Mueller came along long after this. He’s looking at things unrelated to the dossier," he said. "And we’re a rule-of-law nation. And it goes for both parties."

Trump has repeatedly criticized Mueller's Russia investigation, and has reportedly tried to fire Mueller in the past. Still, Speaker Paul Ryan, R-Wis., said Tuesday that he was confident Trump wouldn't dismiss Mueller.

“The special counsel should be free to follow through his investigation to its completion without interference,” Ryan said. “I am confident that he’ll be able to do that. I’ve received assurances that his firing is not even under consideration.”

Sen. Richard Blumenthal called on Republicans to "stand up and speak out."

"If the president is not deterred forcefully and immediately, he will continue down the path of our constitutional crisis … which will bring us another Saturday night massacre with even more dire consequences," he said. "The Republicans who are failing to speak out and stand up now are doing a disservice to democracy."

Contributing: Deirdre Shesgreen and Eliza Collins, USA TODAY, and Dan Nowicki, The Arizona Republic. Follow Jessica Estepa on Twitter: @jmestepa