HIGH-PROFILE supporters of Donald Trump are turning on the man investigating Russian interference in the US election and possible collusion with the President’s campaign — with one suggesting Trump was considering “terminating” him.

As special counsel Robert Mueller builds his legal team, Trump’s allies have begun raising questions about the former FBI director’s impartiality, implying he cannot be trusted to lead the probe.

The comments come amid increasing frustration at the White House and among Trump supporters that the investigation will overshadow the President’s agenda for months to come — a prospect that has Democrats salivating.

“Republicans are delusional if they think the special counsel is going to be fair. Look who he is hiring,” tweeted former House of Representatives speaker Newt Gingrich, an informal Trump adviser.

Just weeks ago, Gingrich heaped praise on Mueller, hailing him as a “superb choice” for special counsel whose reputation was “impeccable for honesty and integrity”.

But after the evidence of former FBI director James Comey last week, Gingrich said he had changed his mind.

“Time to rethink,” he tweeted on Monday, citing Mueller’s hiring decisions and Comey’s admission that he instructed a friend to share with reporters notes he had taken of his private conversations with Trump in order to force the appointment of special counsel.

Conservative commentator Ann Coulter offered a similar message, tweeting: “Now that we know Trump is not under investigation, Sessions should take it back & fire Mueller.”

Trump’s friend Chris Ruddy, CEO of Newsmax, went even further, suggesting the President was already thinking about “terminating” Mueller.

“I think he’s considering perhaps terminating the special counsel,” Ruddy said in an interview with Judy Woodruff of PBS NewsHour.

“I think he’s weighing that option.”

The talk about dismissing Mueller appeared to be coming from Trump allies – including some close to White House strategist Steve Bannon – who are increasingly frustrated with the prospect of a long and winding probe.

They say Trump did not collude with Russia and see the investigation as a politically-motivated sham that handicaps his ability to execute his agenda, according to one person who advises the White House on how to handle the probe.

Ruddy appeared to be basing his remarks, at least in part, on comments from Jay Sekulow, a member of Trump’s legal team, who told ABC in an interview on Sunday that he was “not going to speculate” on whether Trump might at some point order deputy attorney general Rod Rosenstein to sack Mueller.

“Look, the President of the United States, as we all know, is a unitary executive. But the President is going to seek the advice of his counsel and inside the government as well as outside,” Sekulow said.

“And I’m not going to speculate on what he will or will not do.”

Still, he added: “I can’t imagine that that issue is going to arise.”

It was not clear whether Ruddy, who speaks to the President often, was basing his remarks on a specific conversation with him or entirely on Sekulow’s comments.

Ruddy was at the White House on Monday to meet government aides, but did not speak to the President, Trump’s press secretary Sean Spicer said.

White House spokeswoman Sarah Huckabee Sanders said: “Chris speaks for himself.”

Peter Carr, a spokesman for Mueller, declined to comment on Ruddy’s remarks.

Under current Justice Department regulations, firing Mueller would have to be done by attorney general Jeff Sessions’s deputy Rosenstein, not the President, though those regulations could theoretically be set aside.

Sessions recused himself from the investigation because of his own conversations with Russian officials during Trump’s transition.