Firing Mueller could prompt a constitutional crisis, experts have said.
President Donald Trump pushed back on a New York Times report on Thursday that said he had considered firing Special Counsel Robert Mueller, the head of the probe into his campaign's ties to Russian influence.
"If I wanted to fire Robert Mueller in December, as reported by the Failing New York Times, I would have fired him. Just more Fake News from a biased newspaper!" Trump tweeted.
The Times story was not alone in portraying Trump as being held back from firing Mueller as the Russia investigation heats up.
The probe took on heightened significance this week when Trump's longtime personal lawyer, Michael Cohen, had his home and offices raided by law enforcement earlier this week.
Jonathan Swan, a White House reporter for the Axios news website, said that the raid forced a "breaking point" in Trump's anger over Special Counsel Robert Mueller's investigations. Swan said those close to Trump fear he may fire Mueller, possibly triggering a "constitutional crisis."
This week Trump channeled an unprecedented level of anger toward the FBI and Department of Justice officials, calling the raid on Cohen "disgraceful situation," "an attack on our country" and "what we all stand for."
"We're in serious territory," said Walter Shaub, a former head of the Office of Government Ethics who served under Trump and President Barack Obama.
"The President of the United States made remarks today that challenge the rule of law," Shaub continued. "That he seems to think he's above the law puts us potentially on a collision course with a constitutional crisis. What alarms me most is people who aren't alarmed."
Republicans have also expressed fear that Trump may fire Mueller.
"Mr. President, if you're watching, I think you're gonna be fine unless you screw this up," Sen. Lindsey Graham of South Carolina said to Fox News anchor Martha MacCallum on Wednesday. "Let the process play out."